CVE-2026-58055

MEDIUM

nghttp2 nghttpx - HTTP Request/Response Smuggling via Upgrade Request with Content-Length

Title source: cna

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.

References (3)

Core 3

Core References

Patch patch

Fix commit (master)

https://github.com/nghttp2/nghttp2/commit/ab28105c4a0197da24f8bfc414bc116055249e1e

View Patch ZIP pw:eip

Third Party Advisory third-party-advisory

VulnCheck Advisory: nghttp2 nghttpx - HTTP Request/Response Smuggling via Upgrade Request with Content-Length

https://www.vulncheck.com/advisories/nghttp2-nghttpx-http-request-response-smuggling-via-upgrade-request-with-content-length

Exploit exploit third-party-advisory

Proof of Concept

https://github.com/bikini/exploitarium/tree/main/nghttp2-nghttpx-upgrade-queue-poison-poc

View Exploit ZIP pw:eip

Scores

CVSS v3 5.4

EPSS 0.0020

EPSS Percentile 10.4%

Attack Vector NETWORK

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

CISA SSVC

Vulnrichment

Exploitation none

Automatable no

Technical Impact partial

Details

CWE

CWE-444

Status published

Products (1)

nghttp2/nghttp2 < 1.69.0 (2 CPE variants)

Published Jun 28, 2026

Tracked Since Jun 28, 2026