CVE-2026-9256
critical · 9.2NGINX 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.
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
Weaknesses
Affected products
| Vendor | Product | Affected 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 | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| 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 |
Check a specific version with /api/v1/cve/match.
References
- https://my.f5.com/manage/s/article/K000161377
- http://www.openwall.com/lists/oss-security/2026/05/22/14
- https://lists.debian.org/debian-lts-announce/2026/06/msg00023.html
- https://access.redhat.com/errata/RHSA-2026:20351
- https://access.redhat.com/errata/RHSA-2026:28212
- https://access.redhat.com/errata/RHSA-2026:28921
- https://access.redhat.com/errata/RHSA-2026:28973
- https://access.redhat.com/errata/RHSA-2026:29151
- https://access.redhat.com/errata/RHSA-2026:29874
- https://access.redhat.com/errata/RHSA-2026:33313
- https://access.redhat.com/errata/RHSA-2026:44481
- https://access.redhat.com/errata/RHSA-2026:58981
- https://access.redhat.com/security/cve/CVE-2026-9256
- https://bugzilla.redhat.com/show_bug.cgi?id=2480746
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9256.json
Query this programmatically:
curl https://evil-db.io/api/v1/cve/CVE-2026-9256