Vulnerability · Published Mar 23, 2026 · Assigned by VulnCheck
CVE-2026-25075strongSwan 4.5.0 < 6.0.5 EAP-TTLS AVP Parsing Integer Underflow
High 7.5
In plain English
A high-severity null pointer dereference in strongSwan from strongSwan. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.1% (higher than 64% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code. Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | strongswan | 5.9.8-5+deb12u3 | DSA-6176-1 |
| Debian:12 | strongswan | 5.9.8-5+deb12u3 | DEBIAN-CVE-2026-25075 |
| Debian:13 | strongswan | 6.0.1-6+deb13u4 | DSA-6176-1 |
| Debian:13 | strongswan | 6.0.1-6+deb13u4 | DEBIAN-CVE-2026-25075 |
| Debian:14 | strongswan | 6.0.5-1 | DEBIAN-CVE-2026-25075 |
| Ubuntu:22.04:LTS | strongswan | 5.9.5-2ubuntu2.5 | USN-8117-1 |
| Ubuntu:22.04:LTS | strongswan | 5.9.5-2ubuntu2.5 | UBUNTU-CVE-2026-25075 |
| Ubuntu:24.04:LTS | strongswan | 5.9.13-2ubuntu4.24.04.2 | USN-8117-1 |
| Ubuntu:24.04:LTS | strongswan | 5.9.13-2ubuntu4.24.04.2 | UBUNTU-CVE-2026-25075 |
| Ubuntu:25.10 | strongswan | 6.0.1-6ubuntu4.2 | UBUNTU-CVE-2026-25075 |
| Ubuntu:25.10 | strongswan | 6.0.1-6ubuntu4.2 | USN-8117-1 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| strongSwan | strongSwan | 4.5.0 – before 6.0.5 |
Weakness: CWE-191, CWE-476 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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
- https://lists.debian.org/debian-lts-announce/2026/03/msg00016.html