CVE-2026-42055
NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module vulnerability
CRITICAL 9.2
At a glance
- Source
- NVD
- EPSS
- EPSS 6.54 % · percentile 94 ()
- State
- PUBLISHED
- Published
- Updated
- Assigner
- f5
- NVD status
- Modified
Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. This vulnerability exists when the proxy_http_version to 2 or grpc_pass directives are used to proxy HTTP/2 traffic, the ignore_invalid_headers directive is set to off, and the large_client_header_buffers directive size is larger than 2 megabytes. A remote, unauthenticated attacker, along with conditions beyond their control, could send large headers while creating an upstream request. This may cause a heap-based 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.
Weaknesses (CWE)
- CWE-122 — Heap-based Buffer Overflow
- CWE-131 — Incorrect Calculation of Buffer Size
- CWE-787 — Out-of-bounds Write
References
- https://my.f5.com/manage/s/article/K000161584
- https://access.redhat.com/security/cve/CVE-2026-42055
- https://bugzilla.redhat.com/show_bug.cgi?id=2489866
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42055.json
- https://access.redhat.com/errata/RHSA-2026:36364
- https://access.redhat.com/errata/RHSA-2026:38847
- https://access.redhat.com/errata/RHSA-2026:36618
- https://access.redhat.com/errata/RHSA-2026:36331
- https://access.redhat.com/errata/RHSA-2026:36639
- https://access.redhat.com/errata/RHSA-2026:46836
- https://access.redhat.com/errata/RHSA-2026:27197
- https://access.redhat.com/errata/RHSA-2026:44481
- https://access.redhat.com/errata/RHSA-2026:58981
Scores
| Version | Score | Vector | Scored by |
|---|---|---|---|
| CVSS 3.1 | HIGH 8.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | f5 |
| CVSS 4.0 | CRITICAL 9.2 | 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 | f5 |
| CVSS 3.1 | HIGH 8.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | redhat-SADP |
| CVSS 4.0 | CRITICAL 9.2 | 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 | NVD · f5sirt@f5.com (Secondary) |
| CVSS 3.1 | HIGH 8.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | NVD · f5sirt@f5.com (Secondary) |
| CVSS 3.1 | HIGH 8.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | NVD · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary) |
European references
- ENISA EUVD · EUVD-2026-37718
- GCVE · GCVE-0-2026-42055
CERT-FR advisories
- CERTFR-2026-AVI-0866 — Multiples vulnérabilités dans Microsoft Azure Linux · cert.ssi.gouv.fr
- CERTFR-2026-AVI-0775 — Multiples vulnérabilités dans Nginx · cert.ssi.gouv.fr
Affected configurations (NVD CPE)
cpe:2.3:a:f5:dos:*:*:*:*:*:nginx:*:*≥ 4.3.0 ≤ 4.7.0cpe:2.3:a:f5:dos:4.9.0:*:*:*:*:nginx:*:*cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*≥ 1.3.0 ≤ 1.6.2cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*≥ 2.0.0 ≤ 2.6.3cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:*≥ 3.5.0 ≤ 3.7.2cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:*≥ 4.0.0 ≤ 4.0.1cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:*≥ 5.0.0 ≤ 5.5.0cpe:2.3:a:f5:nginx_instance_manager:*:*:*:*:*:*:*:*≥ 2.17.0 ≤ 2.22.0cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*≥ 1.0.0 ≤ 1.30.2cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*≥ 1.31.0 ≤ 1.31.1cpe:2.3:a:f5:nginx_plus:*:*:*:*:long-term_support:*:*:*≥ 37.0.0.1 < 37.0.2.1cpe:2.3:a:f5:nginx_plus:*:*:*:*:continuous_releases:*:*:*≥ r33 < r36cpe:2.3:a:f5:nginx_plus:r36:-:*:*:continuous_releases:*:*:*cpe:2.3:a:f5:nginx_plus:r36:p1:*:*:continuous_releases:*:*:*cpe:2.3:a:f5:nginx_plus:r36:p2:*:*:continuous_releases:*:*:*cpe:2.3:a:f5:nginx_plus:r36:p3:*:*:continuous_releases:*:*:*cpe:2.3:a:f5:nginx_plus:r36:p4:*:*:continuous_releases:*:*:*cpe:2.3:a:f5:nginx_plus:r36:p5:*:*:continuous_releases:*:*:*cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*≥ 4.10.0 ≤ 4.16.0cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*≥ 5.2.0 ≤ 5.8.0cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*≥ 5.9.0 ≤ 5.13.1cpe:2.3:a:redhat:discovery:-:*:*:*:*:*:*:*cpe:2.3:a:redhat:hardened_images:-:*:*:*:*:*:*:*cpe:2.3:a:redhat:update_infrastructure:*:*:*:*:*:*:*:*≥ 5.0 < 5.2cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*cpe:2.3:o:redhat:enterprise_linux:9.0:*:*:*:*:*:*:*cpe:2.3:o:redhat:enterprise_linux:10.0:*:*:*:*:*:*:*
Affected products
| Product | Versions |
|---|---|
| F5 · NGINX Open Source | affected 1.13.10 < 1.31.2 ; affected 1.30.2 < 1.30.3 |
| F5 · NGINX Plus | affected 37.0 < 37.0.2.1 ; affected R36 < R36 P6 |
Sources
| Source | Licence |
|---|---|
| CVE List (CVEProject cvelistV5) | CVE Program Terms of Use |
| EPSS (FIRST.org) | FIRST — attribution requested |
| ENISA EUVD | ENISA — reproduction authorised, source acknowledged |
| CERT-FR (ANSSI) | Licence Ouverte / Etalab 2.0 |
| NVD (NIST) via fkie-cad/nvd-json-data-feeds | Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD |