A defect in the caching_sha2_password authentication plugin causes the server to crash when it receives an excessively large packet during the authentication process. The bug arises because the sha256_crypt_r routine uses the alloca function, which can exhaust stack resources, leading to an abrupt termination of the MariaDB Server process. The result is a denial‑of‑service condition that disrupts database availability for all users.

MariaDB Server versions prior to 11.4.10, all 11.5.x releases up to and including 11.8.5, and 12.x versions preceding 12.2.2 are affected when the caching_sha2_password authentication plugin is installed and user accounts are configured to use it.

The entry has a CVSS score of 6.5, indicating a moderate severity, and an EPSS score of less than 1%, suggesting a low likelihood of exploitation in the wild. It is not listed in the CISA KEV catalog. The vulnerability is exploitable remotely by any client that can establish a connection to the server and supply a large packet during authentication with the caching_sha2_password plugin. The attack requires no privileged credentials and results only in service disruption; the attacker loses confidentiality and integrity is not affected. The likely attack vector is network‑based, so any exposed MariaDB instance could be vulnerable if the plugin is active.