{"id":"CVE-2026-12233","title":"Uninitialized mutex in TLS trusted-credential backend causes kernel NULL-deref DoS under contention","summary":"The PSA Protected Storage credential backend (subsys/net/lib/tls_credentials/tls_credentials_trusted.c) declared its credential-store mutex as a plain zero-filled static struct k_mutex credential_lock; and never called k_mutex_init() on …","severity":"medium","cvss":5.9,"cvssVector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","cwe":["CWE-665"],"vendor":"zephyrproject","product":"zephyr","affected":["zephyr >= 3.2.0 < 4.3.2","zephyr >= 4.4.0 < 4.4.2"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-08-13T15:09:49.771424Z"},"published":"2026-08-12","updated":"2026-11-04","sourceUpdated":"2026-11-04T04:59:22.323Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-12233","references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/29581d586f3d68ec8bb1448b522e5470d4a06aa9","label":"Fix commit"},{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-57c4-xcq2-fqj7","label":"GHSA-57c4-xcq2-fqj7"}],"tags":["cve.org"],"epss":0.00506,"epssPercentile":0.43341,"ingestedAt":"2026-11-05T20:33:06.702Z","slug":"CVE-2026-12233","body":"## Overview\n\nThe PSA Protected Storage credential backend (subsys/net/lib/tls_credentials/tls_credentials_trusted.c) declared its credential-store mutex as a plain zero-filled static struct k_mutex credential_lock; and never called k_mutex_init() on it. A statically zero-filled k_mutex has an uninitialized wait queue (its dlist head/tail are NULL instead of the self-referential sentinels that k_mutex_init/K_MUTEX_DEFINE install). The uncontended lock path does not touch the wait queue, so the defect is latent and serialized use behaves correctly.\n\nWhen two execution contexts contend on the lock, k_mutex_lock() pends the blocking thread on the wait queue via z_pend_curr(), which calls sys_dlist_append() on the zeroed list and dereferences a NULL tail pointer (tail->next = node), faulting the kernel. The lock is held during TLS handshake credential loading and by all credential add/get/delete operations, so a deployment performing concurrent TLS handshakes (for example a server handling multiple simultaneous connections from a remote peer) or a credential-management operation concurrent with a handshake can trigger the dereference.\n\nThe impact is a denial of service: a deterministic kernel panic / device reset on the first contention. There is no memory corruption beyond the NULL dereference and no confidentiality or integrity impact; mutual exclusion on the fast path remains correct. Exposure is limited to builds with CONFIG_TLS_CREDENTIALS_BACKEND_PROTECTED_STORAGE enabled (PSA Protected Storage / TF-M platforms); the default volatile RAM backend initializes its lock correctly and is unaffected.\n\nThe fix initializes the mutex statically with K_MUTEX_DEFINE(credential_lock), providing a valid wait queue so the contended path no longer touches a NULL list.\n\n## Affected\n\n- `zephyr >= 3.2.0 < 4.3.2`\n- `zephyr >= 4.4.0 < 4.4.2`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":33,"depthScoreParts":{"impact":32.5,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}