CVE-2026-54388: tinyproxy · HTTP Request/Response Smuggling
Affects tinyproxySource CVE Database V5
Public exploit available · CVSS 9.3 Critical.
Data as of 8 Nov 2026, 14:34 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 9.3 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 9.1 |
- CISA SSVC
- Exploitation
- Proof of concept is public or traded
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-06-18.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 17 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CISA SSVC: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by VulnCheck
, 5 days before disclosure
CVE published
on cve.org
, t = 0
CISA SSVC assessment
proof of concept public
, 20 hours after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA SSVC, the Metasploit, Exploit-DB and nuclei-templates index as of 8 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| tinyproxytinyproxy | Affected
| Fixed in– |
GitHubtinyproxypkg:github/tinyproxyOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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.
References
- github.com/tinyproxy/tinyproxy/issues/609 (opens in a new tab)
- github.com/tinyproxy/tinyproxy/pull/610 (opens in a new tab)
- github.com/tinyproxy/tinyproxy/commit/364cdb67e0ea00a8e4a7037e2693e0711e816adb (opens in a new tab)
- vulncheck.com/advisories/tinyproxy-http-request-smuggling-via-duplicate-content-length-headers (opens in a new tab)