What is CVE-2026-54388?

CVE-2026-54388 is a critical-severity vulnerability in Tinyproxy, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 9.1/10. Published 2026-06-17.

How severe is CVE-2026-54388?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Tinyproxy

CVE-2026-54388

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…

Vulnerability class: HTTP Request Smuggling

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

Affected products

Tinyproxy — versions 0, 364cdb67e0ea00a8e4a7037e2693e0711e816adb

Weakness classification (CWE)

CWE-444 — Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling)

References

disclosure@vulncheck.com (patch)
disclosure@vulncheck.com (technical-description)
disclosure@vulncheck.com (issue-tracking)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-54388?: CVE-2026-54388 is a critical-severity vulnerability in Tinyproxy, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 9.1/10. Published 2026-06-17.
How severe is CVE-2026-54388?: Critical severity. CVSS v3 base score is 9.1 out of 10.