CVE-2026-42055
Last modified
CVE-2026-42055 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_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. EPSS estimates a 4.25% chance of exploitation in the next 30 days.
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.
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 | 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, <= 2.6.3 |
| 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, <= 5.5.0 |
| F5 | Nginx Instance Manager | >= 2.17.0, <= 2.22.0 |
| F5 | Nginx Open Source | >= 1.0.0, <= 1.30.2 |
| F5 | Nginx Open Source | >= 1.31.0, <= 1.31.1 |
| F5 | Nginx Plus | >= 37.0.0.1, < 37.0.2.1 |
| F5 | Nginx Plus | >= r33, < r36 |
| F5 | Nginx Plus | r36 |
| F5 | Waf | >= 4.10.0, <= 4.16.0 |
| F5 | Waf | >= 5.2.0, <= 5.8.0 |
| F5 | Waf | >= 5.9.0, <= 5.13.1 |
| Redhat | Discovery | All versions |
| Redhat | Hardened Images | All versions |
| Redhat | Update Infrastructure | >= 5.0, < 5.2 |
| Redhat | Enterprise Linux | 8.0 |
| Redhat | Enterprise Linux | 9.0 |
| Redhat | Enterprise Linux | 10.0 |
References
- https://my.f5.com/manage/s/article/K000161584Vendor Advisory
- https://access.redhat.com/errata/RHSA-2026:27197Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:36331Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:36364Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:36618Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:36639Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:38847Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:44481Third Party Advisory
- https://access.redhat.com/errata/RHSA-2026:46836Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2026-42055Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2489866Third Party Advisory, Issue Tracking
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42055.jsonThird Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
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