Executive brief
MISP is a threat intelligence platform that tracks security events, including failed authentication attempts. When Redis (an external cache service) becomes unavailable, the authentication-failure logging stops entirely, meaning security incidents go unrecorded and undetected during the outage. This reduces the ability to identify and respond to attack attempts.
Technical details
MISP uses Redis to throttle duplicate authentication-failure log entries. The vulnerable _shouldLog() function has a fail-closed flaw: it returns false both when throttling is active and when Redis cannot be reached. When User->setupRedis() fails to connect to Redis, the logging mechanism incorrectly rejects all authentication-failure events, silencing security logs for the duration of the Redis outage. The root cause is improper error handling that conflates throttling logic with connection failure. This is a logic error in the logging flow that affects all MISP versions up to 2.5.45. The fix, available on GitHub, corrects _shouldLog() to distinguish between "Redis unavailable" and "throttle key present" conditions.
Affected products
- MISP MISP ≤2.5.45
Timeline
- 2026-09-15: disclosed
- 2026-09-15: patched: Fix available on GitHub commit a39b25d2f