PT-2026-53087 · Undefined · Undefined

Published 2026-06-28 · Updated 2026-06-28 · CVE-2026-58055

NVD

CVSS v3.1

5.4

Medium

Base vector

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

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.

Exploit

Fix

HTTP Request/Response Smuggling

Weakness Enumeration

CWE-444

Related Identifiers

CVE-2026-58055

Affected Products

Undefined

References · 4

• 🔥 https://github.com/bikini/exploitarium/tree/main/nghttp2-nghttpx-upgrade-queue-poison-poc · Exploit
• https://nvd.nist.gov/vuln/detail/CVE-2026-58055 · Security Note
• https://github.com/nghttp2/nghttp2/commit/ab28105c4a0197da24f8bfc414bc116055249e1e · Note
• https://vulncheck.com/advisories/nghttp2-nghttpx-http-request-response-smuggling-via-upgrade-request-with-content-length · Note