VULNERABILITY INTELLIGENCE

CVE-2026-58055

CVSS score5.4 MEDIUM
EPSS probability0.25%
CISA KEVNot currently listed
Published2026-06-28
Last modified2026-10-25
CVSS vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N

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.

Weakness classification

  • disclosure@vulncheck.com: CWE-444

Primary references