CVE-2026-58055

CVE Details

Release Date:	2026-06-28
Impact:	Moderate	What is this?

Description

nghttp2's nghttpx proxy through 1.69.0 forwards an HTTP/1.1 Upgrade request that also carries a Content-Length header and body onto reusable keep-alive backend connections, re-adding the Upgrade and Connection headers while passing Content-Length verbatim. A backend that resolves the resulting ambiguous message in the attacker's favor enables HTTP request/response smuggling and cross-client response-queue poisoning.

See more information about CVE-2026-58055 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	5.4
Vector String:	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
Version:	3.1
Attack Vector:	Network
Attack Complexity:	High
Privileges Required:	None
User Interaction:	None
Scope:	Changed
Confidentiality Impact:	Low
Integrity Impact:	Low
Availability Impact:	None

Errata information

Platform	Errata	Release Date
Oracle Linux version 10 (nghttp2)	ELSA-2026-54650	2026-08-13
Oracle Linux version 9 (nghttp2)	ELSA-2026-54662	2026-08-13