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CVE-2026-543879.3CriticalCWE-444

CVE-2026-54387: tinyproxy vulnerability

tinyproxy

Vendor fix available · Affected: tinyproxy · Exploitation: not established

ExploitationNot established

Not in CISA KEV as of catalogue 2026.11.13 (13 Nov)

  1. In CISA KEV: not seen
  2. Exploited (reported): not seen
  3. Scanning observed: not seen
  4. Proof of concept public: not seen
  5. Not establishedNothing in the sources we check
0.4%probability of exploitation in the next 30 days
38th percentile
050100

Higher than 38% of scored CVEs

9.3CriticalCVSS 4.0
LowCrit.

DescriptionNVD

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.

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas
Exploitation
Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV
Not listed
Public check
No public nuclei template
Vendor
tinyproxy
Published
June 2026

Coverage1 article · 1 outlet

First in our coverage: SecurityOnline, 23 Jun.

  1. Tinyproxy flaws allow HTTP request smuggling, urge patch now
    SecurityOnline · first in our coverage · mentions it in passing

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References