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 :
May 23, 2026, 1:16 a.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | 9dacffd4-cb11-413f-8451-fbbfd4ddc0ab | ||||
| CVSS 3.1 | HIGH | MITRE-CVE | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| 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 12 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.
| URL | Resource |
|---|---|
| https://my.f5.com/manage/s/article/K000161377 | |
| http://www.openwall.com/lists/oss-security/2026/05/22/14 |
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).
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
None
Dockerfile Shell Makefile 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 HTML
DSA and DLA for Debian last 14 days
Python
SecDB - Security Feeds
cve security-feeds vulnerability
TOP All bugbounty pentesting CVE-2023- POC Exp RCE example payload Things
bugbounty cve exp exploit payload poc rce vulnerability
Shell
📡 PoC auto collect from GitHub. ⚠️ Be careful Malware.
security cve exploit poc 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.
-
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 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