CVE-2025-21871: linux kernel — Fix

Description

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.

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CVSS v3.1 Score

5.5

MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Weakness Type (CWE)

CWE-835 CWE-835

Affected Products

Vendor	Product	Versions
linux	linux_kernel	4.12 — 5.4.291
linux	linux_kernel	5.5 — 5.10.235
linux	linux_kernel	5.11 — 5.15.179
linux	linux_kernel	5.16 — 6.1.130
linux	linux_kernel	6.2 — 6.6.80
linux	linux_kernel	6.7 — 6.12.17
linux	linux_kernel	6.13 — 6.13.5
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All

References

Advisories & Patches

https://git.kernel.org/stable/c/0180cf0373f84fff61b16f8c062553a13dd7cfca https://git.kernel.org/stable/c/21234efe2a8474a6d2d01ea9573319de7858ce44 https://git.kernel.org/stable/c/3eb4911364c764572e9db4ab900a57689a54e8ce https://git.kernel.org/stable/c/70b0d6b0a199c5a3ee6c72f5e61681ed6f759612 https://git.kernel.org/stable/c/c0a9a948159153be145f9471435695373904ee6d https://git.kernel.org/stable/c/d61cc1a435e6894bfb0dd3370c6f765d2d12825d https://git.kernel.org/stable/c/ec18520f5edc20a00c34a8c9fdd6507c355e880f https://git.kernel.org/stable/c/fd9d2d6124c293e40797a080adf8a9c237efd8b8

Other References

https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html

Frequently Asked Questions

What is CVE-2025-21871? +

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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-21871? +

CVE-2025-21871 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-21871? +

CVE-2025-21871 affects products from linux, specifically: linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-21871? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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