Description
Stunnel 4.00, and 3.24 and earlier, leaks a privileged file descriptor returned by listen(), which allows local users to hijack the Stunnel server.
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 | stunnel | 2:3.26 | — |
| Debian 13 | stunnel4 | 2:4.04 | — |
| Debian 12 | stunnel4 | 2:4.04 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
Exploit-DB 1
- Stunnel 3.24/4.00 - Daemon Hijacking EDB-91 · local · Sep 5, 2003 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
References
- 20030903 Stunnel-3.x Daemon Hijacking mailing-list
- CLA-2003:736 vendor-advisory
- MDKSA-2003:108 vendor-advisory
- RHSA-2003:297 vendor-advisory