CVE-2026-54387

EUVD-2026-37789
Tinyproxy through 1.11.3, fixed in commit ff45d3b, fails to reconcile conflicting Content-Length and Transfer-Encoding: chunked headers, forwarding both verbatim to the backend while using Content-Length to determine how many request body bytes to consume. Remote attackers can desynchronize the proxy and backend parser state, allowing injection of arbitrary HTTP requests to the backend to enable cache poisoning, access control bypass, and request hijacking.
HTTP Request/Response Smuggling
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
VulnCheckCNA
9.1 CRITICAL
NETWORK
LOW
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: 36%
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
tinyproxy_projecttinyproxy
𝑥
≤ 1.11.3
CNA
Debian logo
Debian Releases
Debian Product
Codename
tinyproxy
bookworm
postponed
bookworm (security)
vulnerable
bullseye
postponed
bullseye (security)
vulnerable
forky
vulnerable
sid
vulnerable
trixie
no-dsa
Ubuntu logo
Ubuntu Releases
Ubuntu Product
Codename
tinyproxy
bionic
needs-triage
focal
needs-triage
jammy
needs-triage
noble
needs-triage
questing
ignored
resolute
needs-triage
trusty
needs-triage