CVE-2026-9256
NGINX ngx_http_rewrite_module vulnerability
Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
INFO
Published Date :
May 22, 2026, 3:16 p.m.
Last Modified :
July 23, 2026, 12:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | 9dacffd4-cb11-413f-8451-fbbfd4ddc0ab | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c | ||||
| CVSS 4.0 | CRITICAL | 9dacffd4-cb11-413f-8451-fbbfd4ddc0ab | ||||
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Update NGINX Plus to the latest version.
- Update NGINX Open Source to the latest version.
- Review and fix rewrite rules with overlapping PCRE captures.
- Disable ASLR if possible and not already enabled.
Public PoC/Exploit Available at Github
CVE-2026-9256 has a 16 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-2026-9256.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-9256 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-2026-9256
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).
None
Dockerfile Python Shell
None
Python
Nginx RCE chain PoC with CVE-2026-9256 and CVE-2026-42945
Python Shell
CVE-2026-9256 Nginx heap buffer overflow POC
Python
Echo assignment - shalev lavyuod
Makefile Shell Dockerfile Python
Local AI-augmented offensive-security scanner: attack surface, CVE+exploitability, client-side intel, lab-mode verification, exploit-chain correlation. Authorization-gated.
Python JavaScript HTML CSS Shell Dockerfile
None
Dockerfile Shell Makefile Python
Community-maintained fork of kubernetes/ingress-nginx with NGINX 1.30.2
fork cve docker helm ingress ingress-controller kubernetes kubernetes-ingress load-balancer nginx nginx130 reverse-proxy security
Lua Makefile Shell Go Template Mustache Go Python Dockerfile HTML JavaScript
poc
Python
cPanel/WHM CVE auditor & patcher — May 2026 batch, zero dependencies.
Shell
Tracking the nginx CVE-2026-9256 rewrite-module heap overflow
nginx security
Shell Makefile Nix CSS HTML
None
WNMP One‑Click Stack | WebDAV · Nginx · PHP · MariaDB · Kernel Tuning
Shell
一个 CVE 漏洞预警知识库，无 exp/poc，部分包含修复方案。A knowledge base of CVE security vulnerability, no PoCs/exploits.
SecDB - Security Feeds
cve security-feeds vulnerability
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-9256 vulnerability anywhere in the article.
-
The Cyber Express
CVE-2026-42533 Exposes Critical Pre-Auth nginx RCE Flaw
A newly disclosed security flaw, CVE-2026-42533, has revealed a critical Pre-Auth nginx vulnerability that could allow attackers to achieve reliable RCE (remote code execution) without authentication. ... Read more
-
The Hacker News
Critical NGINX Vulnerability Can Crash Workers and May Allow Remote Code Execution
F5 has shipped fixes for a critical nginx flaw that lets a remote, unauthenticated attacker trigger a heap buffer overflow in the worker process with crafted HTTP requests. CVE-2026-42533 was patched ... Read more
-
CybersecurityNews
Nginx-poolslip Vulnerability Enables DoS and Code Execution Attacks — Patch Now!
A newly disclosed flaw in one of the world’s most widely deployed web servers is forcing administrators into another emergency patch cycle. Tracked as CVE-2026-9256 and publicly nicknamed nginx-poolsl ... Read more
The following table lists the changes that have been made to the
CVE-2026-9256 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]
Jul. 23, 2026
Action Type Old Value New Value Added Translation Title: NGINX Plus y NGINX Open Source de F5, Description: NGINX Plus y NGINX Open Source tienen una vulnerabilidad en el módulo ngx_http_rewrite_module. Esta vulnerabilidad existe cuando una directiva de reescritura utiliza un patrón de expresión regular (regex) con capturas de expresiones regulares compatibles con Perl (PCRE) distintas y superpuestas (por ejemplo, ^/((.*))$) y una cadena de reemplazo que hace referencia a múltiples de dichas capturas (por ejemplo, $1$2) en un contexto de redirección o de argumentos. Un atacante no autenticado, junto con condiciones fuera de su control, puede explotar esta vulnerabilidad enviando solicitudes HTTP manipuladas. Esto puede causar un desbordamiento de búfer de pila en el proceso de trabajador de NGINX, lo que lleva a un reinicio. Además, los atacantes pueden ejecutar código en sistemas con la aleatorización del espacio de direcciones (ASLR) deshabilitada o cuando el atacante puede eludir ASLR. Nota: Las versiones de software que han alcanzado el fin del soporte técnico (EoTS) no se evalúan. -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jul. 15, 2026
Action Type Old Value New Value Changed Affected [{'cpes': ['cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 10)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:8::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 8)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 9)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9::crb'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:discovery:2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat Discovery 2', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:hummingbird:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Hardened Images', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:insights_proxy:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Lightspeed proxy 1', 'defaultStatus': 'affected'}] [{'cpes': ['cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 10', 'versions': [{'status': 'unaffected', 'version': '2:1.26.3-6.el10_2.4', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'nginx', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:8'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 8', 'versions': [{'status': 'unaffected', 'version': '8100020260611094050.489197e6', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'nginx:1.24', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 9', 'versions': [{'status': 'unaffected', 'version': '9080020260610161820.9', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'nginx:1.24', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 9', 'versions': [{'status': 'unaffected', 'version': '2:1.20.1-28.el9_8.3', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'nginx', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux 9', 'versions': [{'status': 'unaffected', 'version': '9080020260609152155.9', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'nginx:1.26', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:discovery:2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat Discovery 2', 'versions': [{'status': 'unaffected', 'version': '1782756541', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'discovery/discovery-ui-rhel9', 'collectionURL': 'https://catalog.redhat.com/software/containers/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:hummingbird:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Hardened Images', 'versions': [{'status': 'unaffected', 'version': '1.30.2-1.hum1', 'lessThan': '*', 'versionType': 'rpm'}], 'packageName': 'nginx-main', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:insights_proxy:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Lightspeed proxy 1', 'packageName': 'insights-proxy/insights-proxy-container-rhel9', 'collectionURL': 'https://access.redhat.com/downloads/content/package-browser/', 'defaultStatus': 'affected'}] -
CVE Modified by 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 10)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:8::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 8)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9::appstream'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux AppStream (v. 9)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/o:redhat:enterprise_linux:10.2'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux CodeReady Linux Builder (v. 10)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:enterprise_linux:9::crb'], 'vendor': 'Red Hat', 'product': 'Red Hat Enterprise Linux CodeReady Linux Builder (v. 9)', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:discovery:2::el9'], 'vendor': 'Red Hat', 'product': 'Red Hat Discovery 2', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:hummingbird:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Hardened Images', 'defaultStatus': 'affected'}, {'cpes': ['cpe:/a:redhat:insights_proxy:1'], 'vendor': 'Red Hat', 'product': 'Red Hat Lightspeed proxy 1', 'defaultStatus': 'affected'}] Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H Added CWE CWE-122 Added Reference https://access.redhat.com/errata/RHSA-2026:20351 Added Reference https://access.redhat.com/errata/RHSA-2026:28212 Added Reference https://access.redhat.com/errata/RHSA-2026:28921 Added Reference https://access.redhat.com/errata/RHSA-2026:28973 Added Reference https://access.redhat.com/errata/RHSA-2026:29151 Added Reference https://access.redhat.com/errata/RHSA-2026:29874 Added Reference https://access.redhat.com/errata/RHSA-2026:33313 Added Reference https://access.redhat.com/security/cve/CVE-2026-9256 Added Reference https://bugzilla.redhat.com/show_bug.cgi?id=2480746 Added Reference https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9256.json -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
Jun. 18, 2026
Action Type Old Value New Value Added Reference https://lists.debian.org/debian-lts-announce/2026/06/msg00023.html -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 17, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-9256', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-05-22T00:00:00+00:00'} -
CVE Modified by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'F5', 'modules': ['ngx_http_rewrite_module'], 'product': 'NGINX Plus', 'versions': [{'status': 'affected', 'version': '37.0', 'lessThan': '37.0.1.1', 'versionType': 'custom'}, {'status': 'affected', 'version': 'R36', 'lessThan': 'R36 P5', 'versionType': 'custom'}, {'status': 'affected', 'version': 'R32', 'lessThan': 'R32 P7', 'versionType': 'custom'}], 'defaultStatus': 'unknown'}, {'vendor': 'F5', 'modules': ['ngx_http_rewrite_module'], 'product': 'NGINX Open Source', 'versions': [{'status': 'affected', 'version': '1.31.0', 'lessThan': '1.31.1', 'versionType': 'custom'}, {'status': 'affected', 'version': '1.30.0', 'lessThan': '1.30.2', 'versionType': 'custom'}, {'status': 'affected', 'version': '0.1.17', 'versionType': 'custom', 'lessThanOrEqual': '0.9.7'}], 'defaultStatus': 'unaffected'}] -
Initial Analysis by [email protected]
Jun. 16, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* versions from (including) r32 up to (including) r36 *cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:* versions from (including) 0.1.17 up to (including) 0.9.7 *cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:* versions from (including) 1.0.0 up to (including) 1.30.1 *cpe:2.3:a:f5:nginx_open_source:1.31.0:*:*:*:*:*:*:* *cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* versions from (including) 37.0.0 up to (excluding) 37.0.1.1 Added Reference Type CVE: http://www.openwall.com/lists/oss-security/2026/05/22/14 Types: Mailing List, Third Party Advisory Added Reference Type F5 Networks: https://my.f5.com/manage/s/article/K000161377 Types: Mitigation, Vendor Advisory -
CVE Modified by af854a3a-2127-422b-91ae-364da2661108
May. 23, 2026
Action Type Old Value New Value Added Reference http://www.openwall.com/lists/oss-security/2026/05/22/14 -
New CVE Received by [email protected]
May. 22, 2026
Action Type Old Value New Value Added Description NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated. Added CVSS V4.0 AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/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:H/I:H/A:H Added CWE CWE-122 Added Reference https://my.f5.com/manage/s/article/K000161377