CVE-2026-54388

Tinyproxy - HTTP Request Smuggling via Duplicate Content-Length Headers

Published Jun 17, 2026 CVSS 4.0 · 9.3 Critical EPSS < 1% KEV · Not listed
Description
Tinyproxy through 1.11.3, fixed in commit 364cdb6, fails to reject requests containing multiple Content-Length headers with differing values, forwarding all duplicate headers to the backend while using the first value 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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Tinyproxy Project
Tinyproxy Project tinyproxy
CPEs cpe:2.3:a:tinyproxy_project:tinyproxy:*:*:*:*:*:*:*:*
Vendors & Products Tinyproxy Project
Tinyproxy Project tinyproxy
Type Values Removed Values Added
First Time appeared Tinyproxy
Tinyproxy tinyproxy
Vendors & Products Tinyproxy
Tinyproxy tinyproxy
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Tinyproxy through 1.11.3, fixed in commit 364cdb6, fails to reject requests containing multiple Content-Length headers with differing values, forwarding all duplicate headers to the backend while using the first value 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.
Title Tinyproxy - HTTP Request Smuggling via Duplicate Content-Length Headers
Weaknesses CWE-444
References
Metrics cvssV3_1

{'score': 9.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N'}

cvssV4_0

{'score': 9.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Nov 8, 2026, 2:05 PM
Reserved
Jun 12, 2026, 8:20 PM
Status
Deferred
Published
Jun 17, 2026, 8:17 PM
Modified
Jul 14, 2026, 10:17 PM