CVE-2026-42055
NGINX ngx_http_proxy_v2_module and ngx_http_grpc_module 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.
How to fix CVE-2026-42055
To remediate CVE-2026-42055, upgrade the affected package to a fixed version below.
- —upgrade to 1.26.3-r2 or later
- —upgrade to 1.30.3 or later
- —upgrade to 1.31.2 or later
Is CVE-2026-42055 being exploited?
Low — EPSS is 3.6%, meaning exploitation activity has not been observed at scale.
Affected packages (3)
- from 0, < 1.26.3-r2
- >= 1.30.0, < 1.30.3, >= 1.31.1, < 1.31.2
- >= 1.13.10, < 1.31.2
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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 |