CVE-2026-9256
Last modified
CVE-2026-9256 is a critical-severity vulnerability rated 9.2/10 on the CVSS scale. 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$2) in a redirect or arguments context. EPSS estimates a 10.06% chance of exploitation in the next 30 days.
Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) 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.
Metrics
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS:4.0/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
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| F5 | Nginx Open Source | >= 0.1.17, <= 0.9.7 |
| F5 | Nginx Open Source | >= 1.0.0, < 1.30.2 |
| F5 | Nginx Open Source | 1.31.0 |
| F5 | Nginx Plus | >= r33, < r36 |
| F5 | Nginx Plus | 37.0.0.1 |
| F5 | Nginx Plus | r32 |
| F5 | Nginx Plus | r36 |
| F5 | Dos | >= 4.3.0, <= 4.7.0 |
| F5 | Dos | 4.9.0 |
| F5 | Nginx Gateway Fabric | >= 1.3.0, <= 1.6.2 |
| F5 | Nginx Gateway Fabric | >= 2.0.0, < 2.6.2 |
| F5 | Nginx Ingress Controller | >= 3.5.0, <= 3.7.2 |
| F5 | Nginx Ingress Controller | >= 4.0.0, <= 4.0.1 |
| F5 | Nginx Ingress Controller | >= 5.0.0, < 5.4.3 |
| F5 | Nginx Instance Manager | >= 2.17.0, < 2.22.1 |
| F5 | Waf | >= 4.10.0, <= 4.16.0 |
| F5 | Waf | >= 5.2.0, <= 5.8.0 |
| F5 | Waf | >= 5.9.0, <= 5.13.0 |
| Redhat | Discovery | All versions |
| Redhat | Hardened Images | All versions |
| Redhat | Update Infrastructure | >= 5.0, < 5.2 |
| Debian | Debian Linux | 11.0 |
| Redhat | Enterprise Linux | 8.0 |
| Redhat | Enterprise Linux | 9.0 |
| Redhat | Enterprise Linux | 10.0 |
References
- https://my.f5.com/manage/s/article/K000161377Mitigation, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2026/06/msg00023.htmlMailing List, Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:20351Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:28212Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:28921Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:28973Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:29151Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:29874Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:33313Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:44481Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2026-9256Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2480746Issue Tracking, Third Party Advisory
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9256.jsonThird Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
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How Strix Helps
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