CVE-2026-42926 PUBLISHED

NGINX ngx_http_proxy_v2_module vulnerability

Assigner: f5
Reserved: 05.05.2026 Published: 13.05.2026 Updated: 13.05.2026

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.

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
CVSS Score: 5.8

Attack Vector	Network	Scope	Changed
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	Low
User Interaction	None	Availability Impact	None

CVSS 3.1

CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:L/SA:N
CVSS Score: 6.3

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	Low
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Product Status

Vendor	F5
Product	NGINX Open Source
Versions	Default: unaffected unaffected from 1.31.0 to * (excl.) affected from 1.29.4 to 1.30.1 (excl.)

Credits

F5 acknowledges Mufeed VH of Winfunc Research, Hcamael of aipyaipy, and 章鱼哥 of aipyaipy for bringing this issue to our attention and following the highest standards of coordinated disclosure. reporter

References

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

Problem Types

CWE-172 Encoding Error CWE