CVE-2026-42926
MediumCVSS 5.8Exploitation Probability (EPSS)
Low risk24th percentile - higher than 24% of all known CVEs
Summary
A vulnerability in NGINX Open Source allows an attacker to inject frame headers and payload bytes to the upstream peer when configured to proxy HTTP/2 and using proxy_set_body.
Risk Assessment
This could lead to unauthorized access to data or manipulation of communication between servers.
Recommendation
It is recommended to avoid using proxy_set_body in HTTP/2 proxy configurations or to upgrade to versions that are not under EoTS.
Other vulnerabilities in NGINX Open Source
See all- CVE-2026-42530High
NGINX Open Source has a vulnerability in the ngx_http_v3_module. When configured with the HTTP/3 QUIC module, a remote unauthenticated attacker, under specific conditions, can use a crafted HTTP/3 session to reopen a QPACK encoder stream, causing a Use-after-Free in the NGINX worker process leading to a restart. On systems with ASLR disabled or bypassed, code execution is possible.
- CVE-2026-27784High
A vulnerability in the 32-bit NGINX Open Source ngx_http_mp4_module module allows an attacker to over-read or over-write worker memory using a crafted MP4 file, potentially causing worker termination. Only 32-bit builds with the module enabled and the mp4 directive in use are affected.
Original NVD description (English source)
When NGINX Open Source is configured to proxy HTTP/2 traffic by setting proxy_http_version to 2, and also uses proxy_set_body, an attacker may be able to inject frame headers and payload bytes to the upstream peer. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.