CVE-2026-54388
Tinyproxy - HTTP Request Smuggling via Duplicate Content-Length Headers
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.
INFO
Published Date :
June 17, 2026, 8:17 p.m.
Last Modified :
July 14, 2026, 10:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-54388
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | CRITICAL | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | CRITICAL | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Update Tinyproxy to a version that includes commit 364cdb6.
- Apply vendor-provided patches for Tinyproxy.
- Configure Tinyproxy to reject ambiguous Content-Length headers.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-54388.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-54388 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-54388
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-54388 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-54388 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by [email protected]
Jul. 14, 2026
Action Type Old Value New Value Changed Affected [{'repo': 'https://github.com/tinyproxy/tinyproxy', 'vendor': 'tinyproxy', 'product': 'tinyproxy', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '1.11.3'}, {'status': 'unaffected', 'version': '364cdb67e0ea00a8e4a7037e2693e0711e816adb', 'versionType': 'git'}], 'defaultStatus': 'affected'}] [{'repo': 'https://github.com/tinyproxy/tinyproxy', 'vendor': 'tinyproxy', 'product': 'tinyproxy', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '1.11.3'}, {'status': 'unaffected', 'version': '364cdb67e0ea00a8e4a7037e2693e0711e816adb', 'versionType': 'git'}], 'packageURL': 'pkg:github/tinyproxy/tinyproxy', 'defaultStatus': 'affected'}] -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 18, 2026
Action Type Old Value New Value Added Reference https://github.com/tinyproxy/tinyproxy/issues/609 Added SSVC {'id': 'CVE-2026-54388', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-18T15:33:31.245200Z'} -
New CVE Received by [email protected]
Jun. 17, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/tinyproxy/tinyproxy', 'vendor': 'tinyproxy', 'product': 'tinyproxy', 'versions': [{'status': 'affected', 'version': '0', 'versionType': 'semver', 'lessThanOrEqual': '1.11.3'}, {'status': 'unaffected', 'version': '364cdb67e0ea00a8e4a7037e2693e0711e816adb', 'versionType': 'git'}], 'defaultStatus': 'affected'}] 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N Added CWE CWE-444 Added Reference https://github.com/tinyproxy/tinyproxy/commit/364cdb67e0ea00a8e4a7037e2693e0711e816adb Added Reference https://github.com/tinyproxy/tinyproxy/issues/609 Added Reference https://github.com/tinyproxy/tinyproxy/pull/610 Added Reference https://www.vulncheck.com/advisories/tinyproxy-http-request-smuggling-via-duplicate-content-length-headers