TI-2026-20255 Aliases CVE-2026-25075 GHSA-frr2-5qjr-h4hw

strongSwan 4.5.0 < 6.0.5 EAP-TTLS AVP Parsing Integer Underflow

MEDIUM 46CWE-191Published 2026-03-23 · Updated 2026-07-14

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-191 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.01052 64th percentileScored 2026-11-07

Public exploit Yes 2 exploit referencesTagged by the CNA

Fix Fixed strongSwan (strongSwan): 6.0.5

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
strongSwan	strongSwan	4.5.0 to before 6.0.5	6.0.5	Patch available	CNA

strongSwan VendorstrongSwan Affected 4.5.0 to before 6.0.5 Fixed in 6.0.5 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:strongswan:strongswan::::::::	—	—	strongSwan

cpe:2.3:a:strongswan:strongswan:*:*:*:*:*:*:*:* Versions — — ·strongSwan

Remediation

Fix · CNA strongSwan (strongSwan) Fixed in 6.0.5

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product

Red Hat

Timeline

2026-10-02 Threatist record created from CVE-2026-25075
2026-10-03 Alias added: GHSA-frr2-5qjr-h4hw

References

Exploit 2

Other 1

https://www.strongswan.org/blog/2026/03/23/strongswan-6.0.5-released.html

TI-2023-22300 strongSwan before 5.9.12 has a buffer overflow and possible unauthenticated remote code… CVSS 3.1CRITICAL 9.8
TI-2015-03374 strongSwan 5.2.2 and 5.3.0 allows remote attackers to cause a denial of service (daemon… CVSS 3.0CRITICAL 9.8
TI-2004-00531 FreeS/WAN 1.x and 2.x, and other related products including superfreeswan 1.x, openswan… CVSS 2.0HIGH 10.0
TI-2023-11610 strongSwan 5.9.8 and 5.9.9 potentially allows remote code execution because it uses a… CVSS 3.1CRITICAL 9.8
TI-2026-21012 strongMan vulnerable to private credential recovery due to key and counter reuse CVSS 4.0HIGH 8.7
TI-2021-20414 In strongSwan before 5.9.5, a malicious responder can send an EAP-Success message too… CVSS 3.1CRITICAL 9.1

See all 52 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences