Description
The server implementation of the EAP-MSCHAPv2 protocol in the eap-mschapv2 plugin in strongSwan 4.2.12 through 5.x before 5.3.4 does not properly validate local state, which allows remote attackers to bypass authentication via an empty Success message in response to an initial Challenge message.
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 | strongswan | 5.3.3-3 | — |
| Debian 13 | strongswan | 5.3.3-3 | — |
| Debian 12 | strongswan | 5.3.3-3 | — |
| Debian 8 | strongswan | 5.2.1-6+deb8u2 | DSA-3398-1 |
| Debian 7 | strongswan | 4.5.2-1.5+deb7u8 | DSA-3398-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 6.0 | strongswan | 4.4.1-5.8 | DLA-345-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | strongswan | 5.1.2-0ubuntu7 | — |
| Ubuntu 14.04 LTS | strongswan | 5.1.2-0ubuntu2.4 | USN-2811-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP1 | strongswan | 5.1.3-22.1 | SUSE-SU-2015:2183-2 |
| SLES 12 | strongswan | 5.1.3-22.1 | SUSE-SU-2015:2183-1 |
| SLES 11 SP4 | strongswan | 4.4.0-6.32.1 | SUSE-SU-2015:2186-1 |
| SLES 11 SP3 | strongswan | 4.4.0-6.32.1 | SUSE-SU-2015:2186-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP1 | strongswan | 5.1.3-22.1 | SUSE-SU-2015:2183-2 |
| SLES for SAP 12 | strongswan | 5.1.3-22.1 | SUSE-SU-2015:2183-1 |
| SLES for SAP 11 SP4 | strongswan | 4.4.0-6.32.1 | SUSE-SU-2015:2186-1 |
| SLES for SAP 11 SP3 | strongswan | 4.4.0-6.32.1 | SUSE-SU-2015:2186-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | strongswan | 5.3.5-1.1 | openSUSE-SU-2024:10579-1 |
Advisories 7
- DLA-345-1 strongswan - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DSA-3398-1 strongswan - security update Debian Security (DSA / DLA) · Mar 9, 2026
- USN-2811-1 strongswan vulnerability Ubuntu Security Notices (USN) · Feb 10, 2026
- openSUSE-SU-2024:10579-1 strongswan-5.3.5-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2015:2186-1 Security update for strongswan SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2015:2183-1 Security update for strongswan SUSE / openSUSE Security Updates · May 2, 2025
- SUSE-SU-2015:2183-2 Security update for strongswan SUSE / openSUSE Security Updates · May 2, 2025
References
- SUSE-SU-2015:2183 vendor-advisory
- https://www.strongswan.org/blog/2015/11/16/strongswan-vulnerability-%28cve-2015-8023%29.html
- openSUSE-SU-2015:2103 vendor-advisory
- 84947 vdb-entry
- DSA-3398 vendor-advisory
- USN-2811-1 vendor-advisory