Description
Stunnel 5.00 through 5.13, when using the redirect option, does not redirect client connections to the expected server after the initial connection, which allows remote attackers to bypass authentication.
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 13 | stunnel4 | 3:5.18-1 | — |
| Debian 12 | stunnel4 | 3:5.18-1 | — |
| Debian 8 | stunnel4 | 3:5.06-2+deb8u1 | DSA-3299-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 | stunnel | 5.00-3.1 | SUSE-SU-2015:1062-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 | stunnel | 5.00-3.1 | SUSE-SU-2015:1062-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | stunnel | 5.65-1.1 | openSUSE-SU-2024:12196-1 |
Advisories 3
- DSA-3299-1 stunnel4 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2015:1062-1 Security update for stunnel SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:12196-1 stunnel-5.65-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- DSA-3299 vendor-advisory
- 74659 vdb-entry
- https://www.stunnel.org/CVE-2015-3644.html
- 1032324 vdb-entry