CVE-2026-56425 misp CVE debrief

Who should care

Organizations using the AAD Authentication Plugin (OAuth 2.0 / Azure Active Directory integration) should be concerned about CVE-2026-56425. This includes entities relying on Azure Active Directory for authentication and authorization processes. The critical severity and high CVSS score indicate a high risk of session hijacking, session fixation attacks, replay attacks, and exposure of sensitive credentials.

Technical summary

The CVE-2026-56425 weaknesses include: using the PHP session identifier (session_id()) as the OAuth state parameter, which could leak valid session tokens; not regenerating the session identifier after successful authentication, making sessions susceptible to session fixation attacks; not implementing a dedicated, single-use nonce for the OAuth state value, weakening CSRF protections; failing to enforce HTTPS for configured OAuth redirect URIs, exposing OAuth authorization codes and access tokens in plaintext; and logging OAuth error responses containing attacker-controlled GET parameters verbatim, leading to log forging or injection. The fix includes introducing a dedicated cryptographically random OAuth state value, single-use state validation and invalidation, constant-time state comparison, session identifier rotation after authentication, enforcement of HTTPS-only redirect URIs, and sanitized logging of OAuth error parameters.

Defensive priority

Defenders should prioritize patching and mitigating CVE-2026-56425 immediately due to its critical severity (CVSS score of 9.3) and potential for significant security breaches through session hijacking, fixation attacks, and exposure of sensitive credentials.

Recommended defensive actions

• Inventory and review AAD Authentication Plugin (OAuth 2.0 / Azure Active Directory integration) usage within the organization.
• Apply the patch introducing a dedicated cryptographically random OAuth state value and single-use state validation.
• Enforce HTTPS for all OAuth redirect URIs to prevent exposure of sensitive credentials in plaintext.
• Regenerate session identifiers after successful authentication to prevent session fixation attacks.
• Review and adjust logging of OAuth error responses to prevent log forging or injection.

Evidence notes

The primary evidence for CVE-2026-56425 comes from the CVE record and NVD detail pages. The affected product appears to be the AAD Authentication Plugin (OAuth 2.0 / Azure Active Directory integration). Defenders should verify the use of PHP session identifiers as OAuth state parameters, session regeneration practices, and HTTPS enforcement for OAuth redirect URIs from official sources.

Official resources