CVE-2026-54388 Details
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.
A vulnerability in Tinyproxy versions through 1.11.3 allows for HTTP request smuggling by mishandling duplicate Content-Length headers. The proxy forwards all duplicate headers to the backend while using the first header's value to determine the request body size. This discrepancy can desynchronize the proxy and backend parsers, enabling the injection of arbitrary HTTP requests into the backend. Such exploitation could lead to cache poisoning, bypassing access controls, and hijacking requests from other users of the proxy.
Users can update to Tinyproxy version 1.11.4 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jun 17, 2026CISA-ADP
Assessed Jun 18, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/tinyproxy/tinyproxy/issues/609 | CISA-ADP | ExploitIssue TrackingTechnical AnalysisVendor |
| https://github.com/tinyproxy/tinyproxy/commit/364cdb67e0ea00a8e4a7037e2693e0711e816adb | [email protected] | Source CodeVendor |
| https://github.com/tinyproxy/tinyproxy/issues/609 | [email protected] | ExploitIssue TrackingTechnical AnalysisVendor |
| https://github.com/tinyproxy/tinyproxy/pull/610 | [email protected] | Issue TrackingVendor |
| https://www.vulncheck.com/advisories/tinyproxy-http-request-smuggling-via-duplicate-content-length-headers | [email protected] | AdvisoryRemedy |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-444 | Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Tinyproxy | <= 1.11.3 (semver) |
CPE
Remediation
| |
Change History
3 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 14, 2026 | CVE Modified | [email protected] |
| Jun 18, 2026 | CVE Modified | CISA-ADP |
| Jun 17, 2026 | New CVE Received | [email protected] |