CVE-2015-3644
Stunnel 5.00 through 5.13, when using the redirect option, does not redirect client connections...
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.
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2015-3644- CVSS 2.0
- 5.8 Medium
AV:N/AC:M/Au:N/C:P/I:P/A:N - Weakness
- CWE-284
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2015-3644- Updated
- 2026-11-02
EUVDEUVD-2015-3682 No score
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.
- Record
EUVD-2015-3682- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-3w38-w685-6793 No score
Stunnel 5.00 through 5.13, when using the redirect option, does not redirect client connections...
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.
- Record
GHSA-3w38-w685-6793- Weakness
- CWE-284
- Updated
- 2026-11-02
OSV No score
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.
- Record
CVE-2015-3644- Updated
- 2026-11-02
OSVDEBIAN-CVE-2015-3644 No score
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.
- Record
DEBIAN-CVE-2015-3644- Updated
- 2026-11-02
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OSVMGASA-2015-0289 No score
Updated stunnel package fixes security vulnerability
Johan Olofsson discovered an authentication bypass vulnerability in Stunnel, a program designed to work as an universal SSL tunnel for network daemons. When Stunnel in server mode is used with the redirect option and certificate-based authentication is enabled with "verify = 2" or higher, then only the initial connection is redirected to the hosts specified with "redirect". This allows a remote attacker to bypass authentication (CVE-2015-3644).
- Record
MGASA-2015-0289- Updated
- 2026-11-02
OSVopenSUSE-SU-2024:12196-1 No score
stunnel-5.65-1.1 on GA media
These are all security issues fixed in the stunnel-5.65-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:12196-1- Updated
- 2026-11-02
OSVSUSE-SU-2015:1062-1 No score
Security update for stunnel
This update fixes an authentication bypass when using the 'redirect' option (CVE-2015-3644, bsc#931517, backport from v5.17).
- Record
SUSE-SU-2015:1062-1- Updated
- 2026-11-02
OSVUBUNTU-CVE-2015-3644 No score
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.
- Record
UBUNTU-CVE-2015-3644- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
stunnel4Debian:12 |
before 3:5.18-1 | 3:5.18-1 |
stunnel4Debian:13 |
before 3:5.18-1 | 3:5.18-1 |
stunnel4Debian:8 |
before 3:5.06-2+deb8u1, plus listed versions 3:5.06-2 |
3:5.06-2+deb8u1 |
stunnelMageia:5 |
before 5.03-4.1.mga5 | 5.03-4.1.mga5 |
stunnelSUSE:Linux Enterprise Server 12 |
before 5.00-3.1 | 5.00-3.1 |
stunnelSUSE:Linux Enterprise Server for SAP Applications 12 |
before 5.00-3.1 | 5.00-3.1 |
stunnelopenSUSE:Tumbleweed |
before 5.65-1.1 | 5.65-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2015-3644 is a medium vulnerability (CVSS 5.8) in Stunnel, published May 14, 2015. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 2.12%, the 81st percentile. Fixed in stunnel4 3:5.18-1.
References
debian.org/security/2015/dsa-3299
securityfocus.com/bid/74659
stunnel.org/CVE-2015-3644.html
securitytracker.com/id/1032324
nvd.nist.gov/vuln/detail/CVE-2015-3644
github.com/advisories/GHSA-3w38-w685-6793
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security-tracker.debian.org/tracker/CVE-2015-3644
advisories.mageia.org/MGASA-2015-0289.html
bugs.mageia.org/show_bug.cgi?id=15891
suse.com/support/update/announcement/2015/suse-su-20151062-1
bugzilla.suse.com/931517
ubuntu.com/security/CVE-2015-3644
cve.org/CVERecord?id=CVE-2015-3644