CVE-2026-78135
Received Received - Intake

Authentication Bypass in strongSwan IKEv2 State Machine

Publication date: 2026-09-11

Last updated on: 2026-09-11

Assigner: MITRE

Description
libcharon in strongSwan 5.9.7 through 6.0.7 mishandles behavioral workflow in the IKEv2 state machine. Because CREATE_CHILD_SA requests are mishandled, there can be an authentication bypass.

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Meta Information

Published
2026-09-11
Last Modified
2026-09-11
Generated
2026-09-11
AI Q&A
2026-09-11
EPSS Evaluated
N/A
NVD
CVE-2026-78135
EUVD
EUVD-2026-75921

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
strongswan strongswan From 5.9.7 (inc) to 6.0.7 (inc)
strongswan strongswan 6.1.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-841 The product supports a session in which more than one behavior must be performed by an actor, but it does not properly ensure that the actor performs the behaviors in the required sequence.

Attack-Flow Graph

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Executive Summary

This vulnerability affects strongSwan versions 5.9.7 through 6.0.7 due to improper handling of CREATE_CHILD_SA requests in the IKEv2 state machine. It allows an unauthenticated peer to establish a Child SA before authentication completes, bypassing authentication under specific configurations.

Detection Guidance

To detect this vulnerability, check the strongSwan version on your system using 'strongswan status' or 'ipsec version'. If the version is between 5.9.7 and 6.0.7, the system is potentially vulnerable. Monitor logs for unusual CREATE_CHILD_SA requests during IKE SA establishment, especially when EAP authentication is involved.

Impact Analysis

An attacker could exploit this to create unauthorized IPsec security associations (SAs), potentially gaining access to protected network traffic. However, remote code execution is not possible. Impact depends on configurations like EAP authentication or roadwarrior setups without virtual IP pools.

Compliance Impact

This vulnerability could lead to unauthorized network access, potentially violating data protection requirements in GDPR or HIPAA by exposing sensitive communications. Organizations using vulnerable versions should patch immediately to maintain compliance.

Mitigation Strategies

Upgrade strongSwan to version 6.1.0 or later. If upgrading is not immediately possible, apply patches provided by the strongSwan team for older releases. Ensure servers are not using vulnerable configurations like EAP without proper IP address pools or explicit remote traffic selectors.

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