Description
strongSwan versions 4.5.0 prior to 6.0.5 contain an integer underflow vulnerability in the EAP-TTLS AVP parser that allows unauthenticated remote attackers to cause a denial of service by sending crafted AVP data with invalid length fields during IKEv2 authentication. Attackers can exploit the failure to validate AVP length fields before subtraction to trigger excessive memory allocation or NULL pointer dereference, crashing the charon IKE daemon.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| strongSwan | strongSwan | 4.5.0 – < 6.0.5 | 6.0.5 |
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 | 6.0.5-1 | — |
| Debian 13 | strongswan | 6.0.1-6+deb13u4 | DSA-6176-1 |
| Debian 12 | strongswan | 5.9.8-5+deb12u3 | DSA-6176-1 |
| Debian 11 | strongswan | 5.9.1-1+deb11u6 | DLA-4512-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 25.10 | strongswan | 6.0.1-6ubuntu4.2 | USN-8117-1 |
| Ubuntu 24.04 LTS | strongswan | 5.9.13-2ubuntu4.24.04.2 | USN-8117-1 |
| Ubuntu 22.04 LTS | strongswan | 5.9.5-2ubuntu2.5 | USN-8117-1 |
| 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 | 5.9.5-2ubuntu2.5+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 | 5.9.14-150700.3.9.1 | SUSE-SU-2026:0980-1 |
| SLES 15 SP6 | strongswan | 5.9.12-150600.3.11.1 | SUSE-SU-2026:0979-1 |
| SLES 15 SP5 | strongswan | 5.9.11-150500.5.14.1 | SUSE-SU-2026:0978-1 |
| SLES 15 SP4 | strongswan | 5.9.11-150400.19.26.1 | SUSE-SU-2026:0981-1 |
| SLES 12 SP5 | strongswan | 5.1.3-26.32.1 | SUSE-SU-2026:1307-1 |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | strongswan | 6.0.4-160000.1.1 | SUSE-SU-2026:21203-1 |
| SLES for SAP 15 SP6 | strongswan | 5.9.12-150600.3.11.1 | SUSE-SU-2026:0979-1 |
| SLES for SAP 15 SP5 | strongswan | 5.9.11-150500.5.14.1 | SUSE-SU-2026:0978-1 |
| SLES for SAP 15 SP4 | strongswan | 5.9.11-150400.19.26.1 | SUSE-SU-2026:0981-1 |
| SLES 16.0 | strongswan | 6.0.4-160000.1.1 | SUSE-SU-2026:21203-1 |
| SLE HPC 15 SP5 | strongswan | 5.9.11-150500.5.14.1 | SUSE-SU-2026:0978-1 |
| SLE HPC 15 SP4 | strongswan | 5.9.11-150400.19.26.1 | SUSE-SU-2026:0981-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | strongswan | 6.0.5-1.1 | openSUSE-SU-2026:10441-1 |
| openSUSE Leap 16.0 | strongswan | 6.0.4-160000.1.1 | openSUSE-SU-2026:20547-1 |
| openSUSE Leap 15.6 | strongswan | 5.9.12-150600.3.11.1 | SUSE-SU-2026:0979-1 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | strongswan | 5.9.14-9 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.
GitHub 1 repository
-
BishopFox/CVE-2026-25075-check ★ 2 · Mar 26, 2026
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 12
- WID-SEC-2026-0825 strongSwan: Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Jun 16, 2026
- USN-8117-1 strongswan vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- SUSE-SU-2026:21203-1 Security update for strongswan SUSE / openSUSE Security Updates · Apr 22, 2026
- openSUSE-SU-2026:20547-1 Security update for strongswan SUSE / openSUSE Security Updates · Apr 22, 2026
- SUSE-SU-2026:1307-1 Security update for strongswan SUSE / openSUSE Security Updates · Apr 15, 2026
- DLA-4512-1 strongswan - security update Debian Security (DSA / DLA) · Mar 27, 2026
- openSUSE-SU-2026:10441-1 strongswan-6.0.5-1.1 on GA media SUSE / openSUSE Security Updates · Mar 27, 2026
- SUSE-SU-2026:0978-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 25, 2026
- SUSE-SU-2026:0979-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 25, 2026
- SUSE-SU-2026:0981-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 25, 2026
- SUSE-SU-2026:0980-1 Security update for strongswan SUSE / openSUSE Security Updates · Mar 25, 2026
- DSA-6176-1 strongswan - security update Debian Security (DSA / DLA) · Mar 23, 2026
References
- https://www.strongswan.org/blog/2026/03/23/strongswan-vulnerability-(cve-2026-25075).html vendor-advisory exploit
- https://www.strongswan.org/blog/2026/03/23/strongswan-6.0.5-released.html release-notes
- https://y637f9qq2x.com/posts/cve-2026-25075/ technical-description exploit
- https://www.vulncheck.com/advisories/strongswan-eap-ttls-avp-parsing-integer-underflow third-party-advisory