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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| tinyproxy | tinyproxy | ≤ 1.11.3 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | tinyproxy | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | tinyproxy | No fix yet | — |
| Ubuntu 26.04 LTS | tinyproxy | No fix yet | — |
| Ubuntu 25.10 | tinyproxy | No fix yet | — |
| Ubuntu 24.04 LTS | tinyproxy | No fix yet | — |
| Ubuntu 20.04 LTS | tinyproxy | No fix yet | — |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | tinyproxy | No fix yet | — |
| Ubuntu Pro 18.04 LTS | tinyproxy | No fix yet | — |
| Ubuntu Pro 16.04 LTS | tinyproxy | No fix yet | — |
| Ubuntu Pro 14.04 LTS | tinyproxy | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | tinyproxy | 1.11.3-3.1 | openSUSE-SU-2026:11060-1 |
| openSUSE Leap 16.0 | tinyproxy | 1.11.3-bp160.2.1 | openSUSE-SU-2026:22133-1 |
Advisories 3
- WID-SEC-2026-1999 Tinyproxy: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 20, 2026
- openSUSE-SU-2026:22133-1 Security update for tinyproxy SUSE / openSUSE Security Updates · Oct 20, 2026
- openSUSE-SU-2026:11060-1 tinyproxy-1.11.3-3.1 on GA media SUSE / openSUSE Security Updates · Jun 19, 2026
References
- Researcher Pull Request issue-tracking
- Maintainer Pull Request issue-tracking patch
- Patch Commit patch
- https://www.vulncheck.com/advisories/tinyproxy-http-request-smuggling-via-duplicate-content-length-headers third-party-advisory