7.5
HIGH
CVSS 3.1
CVE-2026-47774
Envoy vulnerable to HTTP/2 memory exhaustion via cookie header size bypass and HPACK amplification
Overview
Description
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a vulnerability in Envoy's HTTP/2 downstream request processing allows an unauthenticated remote client to trigger excessive memory consumption, potentially resulting in OOM termination of the Envoy process and denial of service. The issue arises from the combination of two behaviors. First, cookie header bytes are not fully accounted for during request header size validation in Envoy. Second, HPACK header block limits in oghttp2/quiche are enforced on encoded bytes without a corresponding limit on total decoded header size. Together, these behaviors allow a malicious client to cause large decoded header allocations while bypassing the intended request header size protections. Versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1 contain a fix. No complete workaround is known short of applying a fix. Possible temporary mitigations include disabling downstream HTTP/2 where operationally feasible; enforcing stricter request header and cookie limits before traffic reaches Envoy; and monitoring Envoy memory usage for abnormal growth under HTTP/2 traffic.
Details
INFO
Published Date :
June 17, 2026, 6:18 p.m.
Last Modified :
Oct. 26, 2026, 11:10 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Impact
Affected Products
The following products are affected by CVE-2026-47774
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework
for assessing the severity of vulnerabilities in software and systems.
We collect and displays CVSS scores from various sources for each CVE.
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c |
Solution
Update Envoy to a patched version to prevent excessive memory consumption and denial of service.
- Update Envoy to version 1.35.11 or later.
- Update Envoy to version 1.36.7 or later.
- Update Envoy to version 1.37.3 or later.
- Update Envoy to version 1.38.1 or later.
References
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-47774.
| URL | Resource |
|---|---|
| https://github.com/envoyproxy/envoy/security/advisories/GHSA-22m2-hvr2-xqc8 | Mitigation Vendor Advisory |
| http://www.openwall.com/lists/oss-security/2026/06/04/15 | Mailing List Mitigation Third Party Advisory |
| https://access.redhat.com/errata/RHSA-2026:26210 | Third Party Advisory |
| https://access.redhat.com/errata/RHSA-2026:26222 | Third Party Advisory |
| https://access.redhat.com/errata/RHSA-2026:26231 | Third Party Advisory |
| https://access.redhat.com/errata/RHSA-2026:26247 | Third Party Advisory |
| https://access.redhat.com/errata/RHSA-2026:27114 | Third Party Advisory |
| https://access.redhat.com/security/cve/CVE-2026-47774 | Third Party Advisory |
| https://bugzilla.redhat.com/show_bug.cgi?id=2487465 | Exploit Issue Tracking Third Party Advisory |
| https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47774.json | Third Party Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-47774 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-47774
weaknesses.
CAPEC-125: Flooding Flooding
CAPEC-130: Excessive Allocation Excessive Allocation
CAPEC-147: XML Ping of the Death XML Ping of the Death
CAPEC-197: Exponential Data Expansion Exponential Data Expansion
CAPEC-229: Serialized Data Parameter Blowup Serialized Data Parameter Blowup
CAPEC-230: Serialized Data with Nested Payloads Serialized Data with Nested Payloads
CAPEC-231: Oversized Serialized Data Payloads Oversized Serialized Data Payloads
CAPEC-469: HTTP DoS HTTP DoS
CAPEC-482: TCP Flood TCP Flood
CAPEC-486: UDP Flood UDP Flood
CAPEC-487: ICMP Flood ICMP Flood
CAPEC-488: HTTP Flood HTTP Flood
CAPEC-489: SSL Flood SSL Flood
CAPEC-490: Amplification Amplification
CAPEC-491: Quadratic Data Expansion Quadratic Data Expansion
CAPEC-493: SOAP Array Blowup SOAP Array Blowup
CAPEC-494: TCP Fragmentation TCP Fragmentation
CAPEC-495: UDP Fragmentation UDP Fragmentation
CAPEC-496: ICMP Fragmentation ICMP Fragmentation
CAPEC-528: XML Flood XML Flood
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-47774 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-47774 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 26, 2026
Action Type Old Value New Value Added Translation Title: envoy de envoyproxy, Description: Envoy es un proxy de borde y de servicio de código abierto diseñado para aplicaciones nativas de la nube. Antes de las versiones 1.35.11, 1.36.7, 1.37.3 y 1.38.1, una vulnerabilidad en el procesamiento de solicitudes HTTP/2 descendentes de Envoy permite a un cliente remoto no autenticado activar un consumo excesivo de memoria, lo que podría resultar en la terminación OOM del proceso de Envoy y denegación de servicio. El problema surge de la combinación de dos comportamientos. Primero, los bytes del encabezado de la cookie no se contabilizan completamente durante la validación del tamaño del encabezado de la solicitud en Envoy. Segundo, los límites del bloque de encabezado HPACK en oghttp2/quiche se aplican a los bytes codificados sin un límite correspondiente en el tamaño total del encabezado decodificado. Juntos, estos comportamientos permiten a un cliente malicioso causar grandes asignaciones de encabezados decodificados mientras elude las protecciones de tamaño de encabezado de solicitud previstas. Las versiones 1.35.11, 1.36.7, 1.37.3 y 1.38.1 contienen una corrección. No se conoce ninguna solución alternativa completa que no sea aplicar una corrección. Las posibles mitigaciones temporales incluyen deshabilitar HTTP/2 descendente donde sea operacionalmente factible; aplicar límites más estrictos para los encabezados de solicitud y las cookies antes de que el tráfico llegue a Envoy; y monitorear el uso de memoria de Envoy para detectar un crecimiento anormal bajo tráfico HTTP/2. -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jul. 20, 2026
Action Type Old Value New Value Changed Affected [{'cpes': ['cpe:/a:redhat:service_mesh:2.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 2.6', 'versions': [{'status': 'unaffected', 'version': '1781604724', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.0::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3', 'versions': [{'status': 'unaffected', 'version': '1781069908', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.1::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.1', 'versions': [{'status': 'unaffected', 'version': '1781070158', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.2', 'versions': [{'status': 'unaffected', 'version': '1781070967', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.3::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.3', 'versions': [{'status': 'unaffected', 'version': '1781094520', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}] [{'cpes': ['cpe:/a:redhat:service_mesh:2.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 2.6', 'versions': [{'status': 'unaffected', 'version': '1781604724', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.0::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.0', 'versions': [{'status': 'unaffected', 'version': '1781069908', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.1::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.1', 'versions': [{'status': 'unaffected', 'version': '1781070158', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.2', 'versions': [{'status': 'unaffected', 'version': '1781070967', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.3::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.3', 'versions': [{'status': 'unaffected', 'version': '1781094520', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}] -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jul. 15, 2026
Action Type Old Value New Value Changed Affected [{'cpes': ['cpe:/a:redhat:service_mesh:2.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 2.6', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.1::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.1', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.2', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.3::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.3', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.0::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3', 'defaultStatus': 'affected'}] [{'cpes': ['cpe:/a:redhat:service_mesh:2.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 2.6', 'versions': [{'status': 'unaffected', 'version': '1781604724', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.0::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3', 'versions': [{'status': 'unaffected', 'version': '1781069908', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.1::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.1', 'versions': [{'status': 'unaffected', 'version': '1781070158', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.2', 'versions': [{'status': 'unaffected', 'version': '1781070967', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.3::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.3', 'versions': [{'status': 'unaffected', 'version': '1781094520', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'openshift-service-mesh/istio-proxyv2-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}] -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jul. 13, 2026
Action Type Old Value New Value Changed Affected [{'cpes': ['cpe:/a:redhat:service_mesh:2.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 2.6', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.0::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.0', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.1::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.1', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.2', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.3::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.3', 'defaultStatus': 'affected'}] [{'cpes': ['cpe:/a:redhat:service_mesh:2.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 2.6', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.1::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.1', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.2', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.3::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.3', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.0::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3', 'defaultStatus': 'affected'}] -
Initial Analysis by [email protected]
Jul. 06, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions up to (excluding) 1.35.11 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.36.0 up to (excluding) 1.36.7 *cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:* versions from (including) 1.37.0 up to (excluding) 1.37.3 *cpe:2.3:a:envoyproxy:envoy:1.38.0:*:*:*:*:*:*:* Added CPE Configuration OR *cpe:2.3:a:redhat:openshift_service_mesh:*:*:*:*:*:*:*:* versions from (including) 2.6 up to (excluding) 2.6.17 *cpe:2.3:a:redhat:openshift_service_mesh:*:*:*:*:*:*:*:* versions from (including) 3.0 up to (excluding) 3.0.12 *cpe:2.3:a:redhat:openshift_service_mesh:*:*:*:*:*:*:*:* versions from (including) 3.1 up to (excluding) 3.1.9 *cpe:2.3:a:redhat:openshift_service_mesh:*:*:*:*:*:*:*:* versions from (including) 3.2 up to (excluding) 3.2.6 *cpe:2.3:a:redhat:openshift_service_mesh:*:*:*:*:*:*:*:* versions from (including) 3.3 up to (excluding) 3.3.4 Added Reference Type GitHub, Inc.: https://github.com/envoyproxy/envoy/security/advisories/GHSA-22m2-hvr2-xqc8 Types: Mitigation, Vendor Advisory Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/06/04/15 Types: Mailing List, Mitigation, Third Party Advisory Added Reference Type redhat-SADP: https://access.redhat.com/errata/RHSA-2026:26210 Types: Third Party Advisory Added Reference Type redhat-SADP: https://access.redhat.com/errata/RHSA-2026:26222 Types: Third Party Advisory Added Reference Type redhat-SADP: https://access.redhat.com/errata/RHSA-2026:26231 Types: Third Party Advisory Added Reference Type redhat-SADP: https://access.redhat.com/errata/RHSA-2026:26247 Types: Third Party Advisory Added Reference Type redhat-SADP: https://access.redhat.com/errata/RHSA-2026:27114 Types: Third Party Advisory Added Reference Type redhat-SADP: https://access.redhat.com/security/cve/CVE-2026-47774 Types: Third Party Advisory Added Reference Type redhat-SADP: https://bugzilla.redhat.com/show_bug.cgi?id=2487465 Types: Exploit, Issue Tracking, Third Party Advisory Added Reference Type redhat-SADP: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47774.json Types: Third Party Advisory -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:/a:redhat:service_mesh:2.6::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 2.6', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.0::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.0', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.1::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.1', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.2', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:service_mesh:3.3::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat OpenShift Service Mesh 3.3', 'defaultStatus': 'affected'}] Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-409 Added Reference https://access.redhat.com/errata/RHSA-2026:26210 Added Reference https://access.redhat.com/errata/RHSA-2026:26222 Added Reference https://access.redhat.com/errata/RHSA-2026:26231 Added Reference https://access.redhat.com/errata/RHSA-2026:26247 Added Reference https://access.redhat.com/errata/RHSA-2026:27114 Added Reference https://access.redhat.com/security/cve/CVE-2026-47774 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2487465 Added Reference https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-47774.json -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-47774', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-17T18:00:56.896750Z'} -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jun. 17, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/06/04/15 -
New CVE Received by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'envoyproxy', 'product': 'envoy', 'versions': [{'status': 'affected', 'version': '< 1.35.11'}, {'status': 'affected', 'version': '>= 1.36.0, < 1.36.7'}, {'status': 'affected', 'version': '>= 1.37.0, < 1.37.3'}, {'status': 'affected', 'version': '>= 1.38.0, < 1.38.1'}]}] Added Description Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a vulnerability in Envoy's HTTP/2 downstream request processing allows an unauthenticated remote client to trigger excessive memory consumption, potentially resulting in OOM termination of the Envoy process and denial of service. The issue arises from the combination of two behaviors. First, cookie header bytes are not fully accounted for during request header size validation in Envoy. Second, HPACK header block limits in oghttp2/quiche are enforced on encoded bytes without a corresponding limit on total decoded header size. Together, these behaviors allow a malicious client to cause large decoded header allocations while bypassing the intended request header size protections. Versions 1.35.11, 1.36.7, 1.37.3, and 1.38.1 contain a fix. No complete workaround is known short of applying a fix. Possible temporary mitigations include disabling downstream HTTP/2 where operationally feasible; enforcing stricter request header and cookie limits before traffic reaches Envoy; and monitoring Envoy memory usage for abnormal growth under HTTP/2 traffic. Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-405 Added CWE CWE-770 Added Reference https://github.com/envoyproxy/envoy/security/advisories/GHSA-22m2-hvr2-xqc8
EPSS is a daily estimate of the probability of exploitation activity
being observed over the next 30 days. Following chart shows the EPSS
score history of the vulnerability.