CVE-2026-56434
NGINX ngx_http_ssi_module vulnerability
Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
INFO
Published Date :
July 15, 2026, 3:16 p.m.
Last Modified :
Aug. 10, 2026, 3:27 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-56434
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.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 9dacffd4-cb11-413f-8451-fbbfd4ddc0ab | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | HIGH | 9dacffd4-cb11-413f-8451-fbbfd4ddc0ab | ||||
| CVSS 4.0 | HIGH | [email protected] |
Solution
- Update NGINX to a fixed version.
- Disable proxy_buffering if SSI and proxy_pass are used.
- Apply relevant vendor patches for NGINX.
Public PoC/Exploit Available at Github
CVE-2026-56434 has a 1 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
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-2026-56434.
| URL | Resource |
|---|---|
| https://my.f5.com/manage/s/article/K000162098 | Vendor 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-2026-56434 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-2026-56434
weaknesses.
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).
WNMP One‑Click Stack | WebDAV · Nginx · PHP · MariaDB · Kernel Tuning
Shell
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-56434 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-56434 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.
-
Initial Analysis by [email protected]
Aug. 10, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:f5:nginx_plus:r36:-:*:*:*:*:*:* *cpe:2.3:a:f5:nginx_plus:r36:p1:*:*:*:*:*:* *cpe:2.3:a:f5:nginx_plus:r36:p2:*:*:*:*:*:* *cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:* versions from (including) 1.3.0 up to (including) 1.6.2 *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 5.2.0 up to (including) 5.8.0 *cpe:2.3:a:f5:nginx_plus:r36:p3:*:*:*:*:*:* *cpe:2.3:a:f5:nginx_plus:r36:p4:*:*:*:*:*:* *cpe:2.3:a:f5:nginx_plus:r36:p5:*:*:*:*:*:* *cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:* versions from (including) 2.0.0 up to (excluding) 2.6.7 *cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* versions from (including) 37.0.0.1 up to (excluding) 37.0.3.1 *cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* versions from (including) r33 up to (excluding) r36 *cpe:2.3:a:f5:nginx_plus:r36:p6:*:*:*:*:*:* *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 5.9.0 up to (excluding) 5.13.4 *cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:* versions from (including) 4.11.0 up to (including) 4.16.0 *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:* versions from (including) 3.5.0 up to (including) 3.7.2 *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:* versions from (including) 5.0.0 up to (excluding) 5.5.3 *cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:long-term_support:*:*:* versions from (including) 2026-lts-r1 up to (excluding) 2026-lts-r4 *cpe:2.3:a:f5:nginx_ingress_controller:4.0.0:*:*:*:continuous_releases:*:*:* *cpe:2.3:a:f5:nginx_ingress_controller:4.0.1:*:*:*:continuous_releases:*:*:* Added Reference Type F5 Networks: https://my.f5.com/manage/s/article/K000162098 Types: Vendor Advisory -
CVE Modified by [email protected]
Jul. 15, 2026
Action Type Old Value New Value Changed Description NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a heap buffer over-read in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 15, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-56434', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-15T15:38:13.231118Z'} -
New CVE Received by [email protected]
Jul. 15, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'F5', 'modules': ['ngx_http_ssi_module'], 'product': 'NGINX Plus', 'versions': [{'status': 'affected', 'version': '37.0.0.1', 'lessThan': '37.0.3.1', 'versionType': 'custom'}, {'status': 'affected', 'version': 'R36', 'lessThan': 'R36 P7', 'versionType': 'custom'}, {'status': 'affected', 'version': 'R33', 'lessThan': '*', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'F5', 'modules': ['ngx_http_ssi_module'], 'product': 'NGINX Open Source', 'versions': [{'status': 'affected', 'version': '1.31.2', 'lessThan': '1.31.3', 'versionType': 'custom'}, {'status': 'affected', 'version': '0.8.11', 'lessThan': '1.30.4', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}] Added Description NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a heap buffer over-read in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process. Impact: This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H Added CWE CWE-416 Added Reference https://my.f5.com/manage/s/article/K000162098