EUVD-2026-75920
GHSA-rfvm-pvfp-c8vq
Severity by source
AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
Tunneled EAP server configuration required (AC:H), low-privilege outer identity prerequisite (PR:L), and successful bypass grants full VPN session access (C:H/I:H).
Primary rating from Vendor (vendor:ubuntu).
CVSS VectorVendor: vendor:ubuntu
Lifecycle Timeline
7DescriptionCVE.org
Missing Inner EAP Method Authentication Details
AnalysisAI
Tunneled EAP authentication in strongSwan before 6.1.0 can be bypassed when the IKEv2 responder fails to properly enforce inner EAP method authentication details, enabling a network attacker with a low-privilege outer-tunnel identity to obtain an authorized VPN session without completing the inner credential exchange. The flaw (CWE-863, Incorrect Authorization) is limited to deployments using tunneled EAP methods such as EAP-TTLS or EAP-PEAP; certificate-only or non-tunneled EAP configurations are not affected. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires: (1) the target strongSwan server must be configured to use a tunneled EAP authentication method (EAP-TTLS, EAP-PEAP, or equivalent) for IKEv2 - this is the critical configuration prerequisite reflected in AC:H; deployments using certificate-only mutual authentication, EAP-MSCHAPv2 without tunneling, or other non-tunneled methods are entirely outside the attack surface; (2) the attacker must be able to reach the IKEv2 server over the network to initiate a session; (3) the PR:L metric indicates the attacker needs at minimum a low-privilege context such as a recognized outer EAP identity to begin the inner exchange. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 7.1 score (AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L) conveys a meaningful real-world threat despite the high complexity qualifier: successful exploitation yields full VPN session access rather than partial information leakage, reflected by C:H/I:H. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | The primary fix is to upgrade to strongSwan 6.1.0, confirmed by the official release at https://github.com/strongswan/strongswan/releases/tag/6.1.0 and the vendor advisory at https://www.strongswan.org/blog/2026/09/07/strongswan-vulnerability-(cve-2026-78134).html. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all strongSwan VPN deployments and document their current versions; if versions prior to 6.1.0 are in use with tunneled EAP authentication (EAP-TTLS or EAP-PEAP), escalate to critical priority. …
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Same weakness CWE-863 – Incorrect Authorization
View allSame technique Authentication Bypass
View allShare
External POC / Exploit Code
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