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pac4j-oidc CVE-2026-82461

| EUVDEUVD-2026-68118 HIGH
Improper Verification of Cryptographic Signature (CWE-347)
2026-08-29 VulnCheck GHSA-4w24-77rp-687q
8.6
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
8.6 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/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
vuln.today AI
8.1 HIGH

Network-exploitable requiring a valid low-privilege account (PR:L); no scope change; availability unaffected as the attack grants access rather than disrupting service.

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/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
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

3
Source Code Evidence Fetched
Aug 29, 2026 - 17:25 vuln.today
Analysis Generated
Aug 29, 2026 - 17:25 vuln.today
CVE Published
Aug 29, 2026 - 16:35 cve.org
HIGH 8.6

DescriptionCVE.org

pac4j-oidc before 6.5.6 fails to verify access token signatures, issuers, audiences, or expiry when extracting Keycloak realm and client roles. Attackers can forge access tokens with administrative roles paired with valid ID tokens to bypass authorization checks in applications relying on pac4j role validation.

AnalysisAI

Privilege escalation in pac4j-oidc before 6.5.6 allows authenticated attackers to forge Keycloak access tokens and claim arbitrary administrative roles without cryptographic validation. The KeycloakRolesAuthorizationGenerator component extracted realm and client role claims directly from access token payloads without verifying signatures, issuers, audiences, or expiration - violating core JWT and OIDC validation requirements. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
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Delivery
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Exploit
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Execution
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Persist
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Impact
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Vulnerability AssessmentAI

Exploitation Exploitation requires three specific conditions: (1) the target application uses pac4j-oidc's `KeycloakRolesAuthorizationGenerator` specifically - general OIDC flows not using this generator are unaffected; (2) Keycloak is configured as the OpenID Connect identity provider; (3) the attacker possesses a valid Keycloak account sufficient to obtain a legitimate ID token (PR:L per CVSS 4.0 vector). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The vendor-provided CVSS 4.0 score of 8.6 accurately reflects the severity: the attack is network-reachable (AV:N), low complexity (AC:L), requires no special attack conditions (AT:N), but does require low-level privileges (PR:L) - the attacker must possess a legitimate Keycloak user account to obtain a valid ID token. … 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 adds access token validation before any Keycloak roles are extracted into the user profile. … Detailed patch versions, workarounds, and compensating controls in full report.

Recommended ActionAI

Within 24 hours, audit your software bill of materials to identify all applications and systems using pac4j-oidc and document their current versions. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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CVE-2026-82461 vulnerability details – vuln.today

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