# CVE-2026-78126: strongSwan NULL pointer dereference in eap-aka plugin

Source: https://junglewise.ai/threats/cve-2026-78126-strongswan-null-pointer-dereference-in-eap-aka-plugin  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-11. Updated: 2026-09-26  
License: CC BY 4.0 with a link back

CVE-2026-78126 · Severity: medium · CVSS 5.9 · Published 2026-09-11

strongSwan is a popular open-source IPsec and IKEv2 implementation used to establish encrypted VPN and site-to-site connections. A NULL pointer dereference in the EAP-AKA authentication module allows an unauthenticated attacker to crash the VPN server by sending a specially crafted synchronization-failure message, causing denial of service. Servers using the default configuration are most vulnerable.

Technologies: [strongSwan](https://junglewise.ai/threats/technologies/strongswan). Vendors: [strongSwan](https://junglewise.ai/threats/vendors/strongswan).

## Quick answers

**Is CVE-2026-78126 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-78126 being exploited in the wild.

**How severe is CVE-2026-78126?** Medium severity, with a CVSS score of 5.9, published 11 September 2026.

**Which products and versions are affected?** strongSwan 4.1.10 through 6.0.7.

**Is there a fix for CVE-2026-78126?** A patch was published on 2026-09-07: Fixed in strongSwan 6.1.0 released September 7, 2026 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-78126 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-78126?** Check whether you run strongSwan at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a NULL pointer dereference in the eap-aka plugin when processing an unexpected AKA-Synchronization-Failure message before the server has issued an AKA-Challenge. The eap-aka plugin implements RFC 4187 and by default requests an identity from the peer before sending a challenge. If a peer responds to the identity request with an AKA-Synchronization-Failure message, the plugin attempts to reuse the RAND value that was never allocated (remaining NULL), causing a crash. No authentication is required; the attacker must be able to reach the VPN server over the network. Remote code execution is not possible. The vulnerability affects strongSwan 4.1.10 through 6.0.7; it was fixed in version 6.1.0 released September 7, 2026.

## Affected products

- strongSwan strongSwan 4.1.10 through 6.0.7

## Timeline

- 2026-09-07: disclosed: Vulnerability disclosed by strongSwan project
- 2026-09-07: patched: Fixed in strongSwan 6.1.0 released September 7, 2026

## References

- [https://github.com/strongswan/strongswan/releases/tag/6.1.0](https://github.com/strongswan/strongswan/releases/tag/6.1.0)
- [https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78126).html](https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78126).html)

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- [strongSwan incorrect identity binding in EAP-PEAP and EAP-TTLS](https://junglewise.ai/threats/cve-2026-78134-strongswan-incorrect-identity-binding-in-eap-peap-and-eap-ttls)
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