EUVD-2026-68119
GHSA-w9jq-4xjw-37gj
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
OIDC callback is network-accessible with no authentication or interaction required; scope unchanged as impact is limited to unauthorized session creation in the target application.
Primary rating from Vendor (VulnCheck).
CVSS VectorVendor: VulnCheck
Lifecycle Timeline
2DescriptionCVE.org
pac4j-oidc before 6.5.6 accepts OIDC callbacks carrying only an access token without authorization code or ID token validation. Attackers can substitute access tokens minted for other clients to create authenticated sessions without proper issuer, audience, nonce, or subject verification.
AnalysisAI
Authentication bypass in pac4j-oidc before 6.5.6 allows remote unauthenticated attackers to establish authenticated sessions by submitting OIDC callback requests carrying only a third-party access token, bypassing issuer, audience, nonce, and subject validation entirely. Applications built on the pac4j Java security framework that use OIDC for single sign-on are vulnerable to token substitution attacks from any attacker who holds a valid access token issued by the same identity provider for any other registered OAuth client. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation targets any application using pac4j-oidc versions before 6.5.6 in an OIDC Authorization Code or hybrid flow configuration. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 score of 6.9 (AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N) correctly reflects that the attack is remotely exploitable without privileges or user interaction, though the per-session impact metrics of Low confidentiality and Low integrity understate the systemic severity of a broken authentication boundary. … 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 | Upgrade pac4j-oidc to version 6.5.6 or later, which enforces that OIDC callbacks must include an authorization code or ID token and performs proper issuer, audience, nonce, and subject validation. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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