Vulnerability 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.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| F5 | Dos | >= 4.3.0, <= 4.7.0 |
| F5 | Nginx Gateway Fabric | >= 1.3.0, <= 1.6.2 |
| F5 | Nginx Ingress Controller | >= 3.5.0, <= 3.7.2 |
| F5 | Nginx Instance Manager | >= 2.17.0, <= 2.22.0 |
| F5 | Nginx Open Source | >= 1.0.0, <= 1.30.2 |
| F5 | Nginx Plus | >= 37.0.0.1, < 37.0.2.1 |
| F5 | Waf | >= 4.10.0, <= 4.16.0 |
| Redhat | Discovery | - |
| Redhat | Hardened Images | - |
| Redhat | Update Infrastructure | >= 5.0, < 5.2 |
| Redhat | Enterprise Linux | 8.0 |
Related Weaknesses (CWE)
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 AdvisoryIssue Tracking
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42055.jsonThird Party Advisory
FAQ
What is CVE-2026-42055?
CVE-2026-42055 is a vulnerability with a CVSS score of 8.1 (HIGH). 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 directiv...
How severe is CVE-2026-42055?
CVE-2026-42055 has been rated HIGH with a CVSS base score of 8.1/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-42055?
Check the references section above for vendor advisories and patch information. Affected products include: F5 Dos, F5 Nginx Gateway Fabric, F5 Nginx Ingress Controller, F5 Nginx Instance Manager, F5 Nginx Open Source.