CVE-2026-9256
NGINX ngx_http_rewrite_module vulnerability
No known exploitation. EPSS puts it in the 85th percentile. A vendor fix is available.
What to do
The vendor has published a fix. Version details are below where the sources state them.
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
2.7% chance of exploitation activity in the next 30 days, which ranks it in the 85th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
- Attention now
Rising.
Lifecycle
33 events over 125 days, from the signal feeds we watch.
- EPSS band changemoderate → lowepss band change
- EPSS band changelow → moderate
- EPSS band change0 → moderateepss band change
- Patch availableworkaround available, record updated
- EPSS band changemoderate → low
- EPSS band changemoderate → 0epss band change
Affected products
- NGINX App Protect DoSNetworking Infrastructure
- NGINX Gateway FabricNetworking Infrastructure
- NGINX Ingress ControllerNetworking Infrastructure
- NGINX PlusNetworking Infrastructure
- NGINX Open SourceNetworking Infrastructure
- NGINX Instance ManagerNetworking Infrastructure
- F5 WAF for NGINXNetworking Infrastructure
- NGINX App Protect WAFNetworking Infrastructure
- NGINX PlusNetworking Infrastructure / load-balancer-proxy
- NGINX Open SourceNetworking Infrastructure / load-balancer-proxy
- dosNetworking Infrastructure / network-management
- nginx gateway fabricNetworking Infrastructure / load-balancer-proxy
- nginx ingress controllerNetworking Infrastructure / load-balancer-proxy
- nginx instance managerNetworking Infrastructure / load-balancer-proxy
- wafNetworking Infrastructure / network-management
And 4 more affected products. See all after sign-in
Technical detail
CVSS 3.1 vector
Open in the CVSS calculatorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Scored 8.1 by NVD.
How it is reached
- Attack Vector NetworkExploitable remotely over the network without any special conditions
- Attack Complexity HighRequires specific conditions like a race condition or non-default configuration
- Privileges Required NoneNo authentication required — anyone can exploit this
- User Interaction NoneNo user interaction needed — fully automated exploitation
Scope
- Scope UnchangedImpact is limited to the vulnerable component itself
Impact if exploited
- Confidentiality HighTotal information disclosure — all data in the component is compromised
- Integrity HighTotal loss of integrity — attacker can modify any data in the component
- Availability HighTotal denial of service — the component is completely unavailable
Weaknesses
ATT&CK techniques
Mapped from the weaknesses above (CWE to ATT&CK), not observed in attacks.
- Privilege EscalationT1068Exploitation for Privilege Escalationhigh confidence
Sources
References in the record
- my.f5.com/manage/s/article/K000161377
- openwall.com/lists/oss-security/2026/05/22/14
- lists.debian.org/debian-lts-announce/2026/06/msg00023.html
And 21 more references. See all after sign-in
In the news
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