CVE-2026-56425
HIGHThe Azure Active Directory (AAD) authentication implementation contained multiple weaknesses in its OAuth 2.0 authorization flow that could allow attackers to bypass important security…
Description
The Azure Active Directory (AAD) authentication implementation contained multiple weaknesses in its OAuth 2.0 authorization flow that could allow attackers to bypass important security guarantees provided by the protocol.
The application used the PHP session identifier (session_id()) as the OAuth state parameter. Because session identifiers are long-lived authentication credentials, exposing them in OAuth redirect URLs could leak valid session tokens through browser history, HTTP Referer headers, reverse proxies, access logs, or third-party infrastructure involved in the authentication flow. If obtained by an attacker, the leaked session identifier could potentially be used for session hijacking.
Additionally, the implementation did not regenerate the session identifier after successful authentication, leaving authenticated sessions susceptible to session fixation attacks where an attacker forces a victim to use a known session identifier before login and later reuses that identifier after authentication.
The OAuth state value was also not implemented as a dedicated, single-use nonce. This weakened CSRF protections and increased the risk of replay attacks against the OAuth callback process.
The authentication flow further failed to enforce HTTPS for the configured OAuth redirect URI. If a non-HTTPS redirect URI was used, OAuth authorization codes and access tokens could traverse the network in plaintext, exposing sensitive credentials to network attackers.
Finally, OAuth error responses containing attacker-controlled GET parameters were logged verbatim. An attacker could inject control characters or crafted log content, leading to log forging, log injection, or corruption of audit records.
The fix introduces:
A dedicated cryptographically random OAuth state value.
Single-use state validation and invalidation.
Constant-time state comparison using hash_equals().
Session identifier rotation after successful authentication.
Enforcement of HTTPS-only redirect URIs.
Sanitized and length-limited logging of OAuth error parameters.
AAD Authentication Plugin (OAuth 2.0 / Azure Active Directory integration)
Affected Products
mispmisp-projectDetection & mitigation playbook
Vendor / applianceDetect
Inventory every misp-project misp deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Fix
Apply the misp-project misp security patch or hotfix for CVE-2026-56425 on the affected version, following the vendor advisory for your exact build.
Workarounds
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2026-56425 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2026-56425. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-56425 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-56425 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.