Description
In the eap-mschapv2 plugin (client-side) in strongSwan before 6.0.3, a malicious EAP-MSCHAPv2 server can send a crafted message of size 6 through 8, and cause an integer underflow that potentially results in a heap-based buffer overflow.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| strongSwan | strongSwan | 4.2.12 – < 6.0.3 | 6.0.3 |
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 | strongswan | 6.0.3-1 | — |
| Debian 13 | strongswan | 6.0.1-6+deb13u2 | DSA-6041-1 |
| Debian 12 | strongswan | 5.9.8-5+deb12u2 | DSA-6041-1 |
| Debian 11 | strongswan | 5.9.1-1+deb11u5 | DLA-4359-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | strongswan | 6.0.1-6ubuntu5 | — |
| Ubuntu 25.10 | strongswan | 6.0.1-6ubuntu4.1 | USN-7841-1 |
| Ubuntu 24.04 LTS | strongswan | 5.9.13-2ubuntu4.24.04.1 | USN-7841-1 |
| Ubuntu 22.04 LTS | strongswan | 5.9.5-2ubuntu2.4 | USN-7841-1 |
| Ubuntu 20.04 LTS | strongswan | No fix yet | — |
Show 11 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro FIPS 20.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro FIPS 18.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro FIPS 16.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro FIPS-updates 22.04 LTS | strongswan | 5.9.5-2ubuntu2.4+Fips1 | — |
| Ubuntu Pro FIPS-updates 20.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro FIPS-preview 22.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro 18.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro 16.04 LTS | strongswan | No fix yet | — |
| Ubuntu Pro 14.04 LTS | strongswan | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | strongswan | 5.9.14-150700.3.3.1 | SUSE-SU-2025:3834-1 |
| SLES 15 SP6 | strongswan | 5.9.12-150600.3.5.2 | SUSE-SU-2025:3855-1 |
| SLES 15 SP5 | strongswan | 5.9.11-150500.5.9.1 | SUSE-SU-2025:3873-1 |
| SLES 15 SP4 | strongswan | 5.9.11-150400.19.20.1 | SUSE-SU-2025:3856-1 |
| SLES 15 SP3 | strongswan | 5.8.2-150200.11.45.1 | SUSE-SU-2025:3857-1 |
Show 12 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 12 SP5 | strongswan | 5.1.3-26.29.1 | SUSE-SU-2025:3904-1 |
| SLES for SAP 16.0 | strongswan | 6.0.1-160000.3.1 | SUSE-SU-2025:21167-1 |
| SLES for SAP 15 SP5 | strongswan | 5.9.11-150500.5.9.1 | SUSE-SU-2025:3873-1 |
| SLES for SAP 15 SP4 | strongswan | 5.9.11-150400.19.20.1 | SUSE-SU-2025:3856-1 |
| SLES for SAP 15 SP3 | strongswan | 5.8.2-150200.11.45.1 | SUSE-SU-2025:3857-1 |
| SLES 16.0 | strongswan | 6.0.1-160000.3.1 | SUSE-SU-2025:21167-1 |
| SLE HPC 15 SP5 | strongswan | 5.9.11-150500.5.9.1 | SUSE-SU-2025:3873-1 |
| SLE HPC 15 SP4 | strongswan | 5.9.11-150400.19.20.1 | SUSE-SU-2025:3856-1 |
| SLE HPC 15 SP3 | strongswan | 5.8.2-150200.11.45.1 | SUSE-SU-2025:3857-1 |
| SUSE Manager Server LTS 4.3 | strongswan | 5.9.11-150400.19.20.1 | SUSE-SU-2025:3856-1 |
| SUSE Manager Proxy LTS 4.3 | strongswan | 5.9.11-150400.19.20.1 | SUSE-SU-2025:3856-1 |
| SUSE Enterprise Storage 7.1 | strongswan | 5.8.2-150200.11.45.1 | SUSE-SU-2025:3857-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | strongswan | 6.0.3-1.1 | openSUSE-SU-2025:15681-1 |
| openSUSE Leap 16.0 | strongswan | 6.0.1-160000.3.1 | openSUSE-SU-2025:20132-1 |
| openSUSE Leap 15.6 | strongswan | 5.9.12-150600.3.5.2 | SUSE-SU-2025:3855-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | strongswan | 5.9.14-r3 | — |
| Alpine v3.23 | strongswan | 5.9.14-r3 | — |
| Alpine v3.22 | strongswan | 5.9.14-r1 | — |
| Alpine v3.21 | strongswan | 5.9.14-r1 | — |
| Alpine v3.20 | strongswan | 5.9.13-r2 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | strongswan | 5.9.14-8 | — |
| Azure Linux 2 (CBL-Mariner) | strongswan | 5.9.10-4 | — |
Advisories 13
- WID-SEC-2025-2427 strongSwan (eap-mschapv2 plugin): Schwachstelle ermöglicht Codeausführung und DoS BSI CERT-Bund (WID) · Jun 16, 2026
- USN-7841-1 strongswan vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- openSUSE-SU-2025:20132-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2025:15681-1 strongswan-6.0.3-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:3873-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:3904-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:3856-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:3857-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:21167-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2025:3855-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 23, 2026
- DSA-6041-1 strongswan - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2025:3834-1 Security update for strongswan SUSE / openSUSE Security Updates · Feb 4, 2026
- DLA-4359-1 strongswan - security update Debian Security (DSA / DLA) · Nov 3, 2025