CVE-2025-21871: Linux Kernel

Medium severity, CVSS 5.5. EPSS: 0.2% chance of exploitation in the next 30 days.

In the Linux kernel, the following vulnerability has been resolved: tee: optee: Fix supplicant wait loop OP-TEE supplicant is a user-space daemon and it's possible for it be hung or crashed or killed in the middle of processing an OP-TEE RPC call. It becomes more complicated when there is incorrect shutdown ordering of the supplicant process vs the OP-TEE client application which can eventually lead to system hang-up waiting for the closure of the client application. Allow the client process waiting in kernel for supplicant response to be killed rather than indefinitely waiting in an unkillable state. Also, a normal uninterruptible wait should not have resulted in the hung-task watchdog getting triggered, but the endless loop would. This fixes issues observed during system reboot/shutdown when supplicant got hung for some reason or gets crashed/killed which lead to client getting hung in an unkillable state. It in turn lead to system being in hung up state requiring hard power off/on to recover.

Affected products

• Linux Linux Kernel: from 4.12, before 5.4.291 (fixed in 5.4.291); from 5.5, before 5.10.235 (fixed in 5.10.235); from 5.11, before 5.15.179 (fixed in 5.15.179); from 5.16, before 6.1.130 (fixed in 6.1.130); from 6.2, before 6.6.80 (fixed in 6.6.80); from 6.7, before 6.12.17 (fixed in 6.12.17); …

Published 2025-03-27. Last modified 2026-06-17.