CVE-2026-42926

MEDIUM

NGINX Open Source 1.29.4-1.30.0 and >=1.31.0 - HTTP/2 Request Smuggling via proxy_set_body

Title source: llm

Description

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.

References (1)

Core 1

Core References

Vendor Advisory vendor-advisory patch

https://my.f5.com/manage/s/article/K000161131

Scores

CVSS v3 5.8

EPSS 0.0002

EPSS Percentile 6.7%

Attack Vector NETWORK

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

CISA SSVC

Vulnrichment

Exploitation none

Automatable yes

Technical Impact partial

Details

CWE

CWE-172

Status published

Products (2)

F5/NGINX Open Source 1.29.4 - 1.30.1

F5/NGINX Open Source 1.31.0

Published May 13, 2026

Tracked Since May 13, 2026