CVE-2026-58055

MEDIUM SEVERITY

CVSS Score & Metrics

Base Score

5.4 / 10

Vector String

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

Vulnerability 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.

Vulnerability Details

Published Date

June 28, 2026

Last Modified

June 28, 2026

CWE ID

CWE-444

Source

NVD

Vendor

nghttp2

Product

nghttp2

External References

https://github.com/bikini/exploitarium/tree/main/nghttp2-nghttpx-upgrade-queue-poison-poc
https://github.com/nghttp2/nghttp2/commit/ab28105c4a0197da24f8bfc414bc116055249e1e
https://www.vulncheck.com/advisories/nghttp2-nghttpx-http-request-response-smuggling-via-upgrade-request-with-content-length

CVE-2026-58055

CVSS Score & Metrics

Vulnerability Description

Vulnerability Details

External References

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