Description
strongSwan before 5.9.8 allows remote attackers to cause a denial of service in the revocation plugin by sending a crafted end-entity (and intermediate CA) certificate that contains a CRL/OCSP URL that points to a server (under the attacker's control) that doesn't properly respond but (for example) just does nothing after the initial TCP handshake, or sends an excessive amount of application data.
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 | 5.9.8-1 | — |
| Debian 13 | strongswan | 5.9.8-1 | — |
| Debian 12 | strongswan | 5.9.8-1 | — |
| Debian 11 | strongswan | 5.9.1-1+deb11u3 | DSA-5249-1 |
| Debian 10 | strongswan | 5.7.2-1+deb10u3 | DLA-3143-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | strongswan | 5.9.5-2ubuntu2.1 | USN-5651-1 |
| Ubuntu 20.04 LTS | strongswan | 5.8.2-1ubuntu3.5 | USN-5651-1 |
| Ubuntu 18.04 LTS | strongswan | 5.6.2-1ubuntu2.9 | USN-5651-1 |
Show 8 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 20.04 LTS | strongswan | 5.8.2-1ubuntu3.fips.3.5 | — |
| Ubuntu Pro FIPS-updates 18.04 LTS | strongswan | 5.6.2-1ubuntu2.fips.2.9 | — |
| Ubuntu Pro FIPS-updates 16.04 LTS | strongswan | 5.3.5-1ubuntu3.fips.3.8.6 | — |
| Ubuntu Pro 16.04 LTS | strongswan | 5.3.5-1ubuntu3.8+esm3 | USN-5651-2 |
| Ubuntu Pro 14.04 LTS | strongswan | 5.1.2-0ubuntu2.11+esm3 | USN-5651-2 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP4 | strongswan | 5.8.2-150400.19.3.3 | SUSE-SU-2022:4197-1 |
| SLES 15 SP3 | strongswan | 5.8.2-150200.11.30.1 | SUSE-SU-2022:4159-1 |
| SLES 12 SP5 | strongswan | 5.1.3-26.23.1 | SUSE-SU-2022:4185-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 12 SP5 | strongswan | 5.1.3-26.23.1 | SUSE-SU-2022:4185-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.4 | strongswan | 5.8.2-150400.19.3.3 | SUSE-SU-2022:4197-1 |
| openSUSE Leap 15.3 | strongswan | 5.8.2-150200.11.30.1 | SUSE-SU-2022:4159-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | strongswan | 5.9.8-r0 | — |
| Alpine v3.23 | strongswan | 5.9.8-r0 | — |
| Alpine v3.22 | strongswan | 5.9.8-r0 | — |
| Alpine v3.21 | strongswan | 5.9.8-r0 | — |
| Alpine v3.20 | strongswan | 5.9.8-r0 | — |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | strongswan | 5.9.8-r0 | — |
| Alpine v3.18 | strongswan | 5.9.8-r0 | — |
| Alpine v3.17 | strongswan | 5.9.8-r0 | — |
| Alpine v3.16 | strongswan | 5.9.5-r2 | — |
| Alpine v3.15 | strongswan | 5.9.1-r4 | — |
| Alpine v3.14 | strongswan | 5.9.1-r3 | — |
| Alpine v3.13 | strongswan | 5.9.1-r2 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 2 (CBL-Mariner) | strongswan | 5.9.8-1 | — |
Advisories 9
- USN-5651-2 strongswan vulnerability Ubuntu Security Notices (USN) · Jun 29, 2026
- USN-5651-1 strongswan vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- DSA-5249-1 strongswan - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-3143-1 strongswan - security update Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2022:4185-1 Security update for strongswan SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2022:4197-1 Security update for strongswan SUSE / openSUSE Security Updates · Feb 4, 2026
- VDE-2023-001 PHOENIX CONTACT: Multiple Vulnerabilities in PLCnext Firmware CERT@VDE · Jun 5, 2025
- SUSE-SU-2022:4159-1 Security update for strongswan SUSE / openSUSE Security Updates · May 2, 2025
- WID-SEC-2022-1598 strongSwan: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · May 5, 2024