A local attacker can cause a denial of service in libkcapi by triggering an infinite loop in the _kcapi_aio_read_all() function. This occurs when an application using the Asynchronous Input/Output (AIO) interface reuses an AIO-enabled handle after a prior completion error, leading to a non-terminating wait loop. The vulnerability is identified as CWE-835 (Loop with Unreachable Exit Condition). It affects libkcapi version 0.12.0. Red Hat has released an update (libkcapi 1.5.1-0.1.hum1) that addresses this issue. The vulnerability has a CVSS v3.1 score of 5.1 (medium severity) with an attack vector of local, high attack complexity, no privileges required, and no user interaction needed. The impact is denial of service due to resource consumption causing unresponsiveness.

The vulnerability causes a persistent denial of service by making the affected application or thread unresponsive due to an infinite loop in the AIO read function. There is no impact on confidentiality or integrity. The denial of service results from resource exhaustion (CPU cycles) caused by the infinite loop.

Applications should avoid initializing libkcapi handles with KCAPI_INIT_AIO if AIO functionality is not strictly required. If AIO must be used, applications should destroy and reinitialize libkcapi handles after any AIO completion error instead of reusing them. Additionally, updating to libkcapi version 1.5.1-0.1.hum1 or later, as provided by Red Hat Hardened Images RPMs, will address this vulnerability.