CVE-2026-42055
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.
Key facts
- CVSS score
- 8.1 (v3.1)
- Severity
- HIGH
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
- CWE-122
- EPSS score
- 6.5% (94th percentile)
- In CISA KEV
- No
- In EU EUVD
- Yes (EUVD-2026-37718)
- Published
- June 17, 2026
- NVD last modified
- September 14, 2026
- Status
- Modified
EU Vulnerability Database (EUVD)
This vulnerability is also tracked by ENISA as EUVD-2026-37718 in the EU Vulnerability Database. Last updated in EUVD on September 14, 2026.
View on the EU Vulnerability DatabaseAffected products
- f5 / dos
- f5 / dos
- f5 / nginx gateway fabric
- f5 / nginx ingress controller
- f5 / nginx instance manager
- f5 / nginx open source
- f5 / nginx plus
- f5 / nginx plus
- f5 / nginx plus
- f5 / nginx plus
- f5 / nginx plus
- f5 / nginx plus
- f5 / nginx plus
- f5 / nginx plus
- f5 / waf
- redhat / discovery
- redhat / enterprise linux
- redhat / enterprise linux
- redhat / enterprise linux
- redhat / hardened images
- redhat / update infrastructure
Certified products that may be affected
31 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.
- Red Hat Enterprise Linux 8 NSS Cryptographic Module - Red Hat, Inc. - FIPS 140 5513 - active
- Red Hat Enterprise Linux 8 Kernel Cryptographic API - Red Hat, LLC - FIPS 140 5461 - active
- Red Hat Enterprise Linux 9 Kernel Cryptographic API - Red Hat, Inc. - FIPS 140 5445 - active
- Red Hat Enterprise Linux 9 libgcrypt - Red Hat, Inc. - FIPS 140 5366 - active
- Red Hat Enterprise Linux 8 Kernel Cryptographic API - Red Hat, Inc. - FIPS 140 5089 - active
See all 31 in the Security Certifications Explorer.
References
- https://access.redhat.com/errata/RHSA-2026:27197(Third Party Advisory)
- https://access.redhat.com/errata/RHSA-2026:36331(Third Party Advisory)
- https://access.redhat.com/errata/RHSA-2026:36364(Third Party Advisory)
- https://access.redhat.com/errata/RHSA-2026:36618(Third Party Advisory)
- https://access.redhat.com/errata/RHSA-2026:36639(Third Party Advisory)
- https://access.redhat.com/errata/RHSA-2026:38847(Third Party Advisory)
- https://access.redhat.com/errata/RHSA-2026:44481(Third Party Advisory)
- https://access.redhat.com/errata/RHSA-2026:46836(Third Party Advisory)
- https://access.redhat.com/errata/RHSA-2026:58981
- https://access.redhat.com/security/cve/CVE-2026-42055(Third Party Advisory)
- https://bugzilla.redhat.com/show_bug.cgi?id=2489866(Issue Tracking, Third Party Advisory)
- https://my.f5.com/manage/s/article/K000161584(Vendor Advisory)
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42055.json(Third Party Advisory)
Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS
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