CVE-2025-21726: padata: avoid UAF for reorder_work

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-02-27 · updated 2026-10-15
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: padata: avoid UAF for reorder_work Although the previous patch can avoid ps and ps UAF for _do_serial, it can not avoid potential UAF issue for reorder_work. This issue can happen just as below: crypto_request crypto_request crypto_del_alg padata_do_serial ... padata_reorder // processes all remaining // requests then breaks while (1) { if (!padata) break; ... } padata_do_serial // new request added list_add // sees the new request queue_work(reorder_work) padata_reorder queue_work_on(squeue->work) ... <kworker context> padata_serial_worker // completes new request, // no more outstanding // requests crypto_del_alg // free pd <kworker context> invoke_padata_reorder // UAF of pd To avoid UAF for 'reorder_work', get 'pd' ref before put 'reorder_work' into the 'serial_wq' and put 'pd' ref until the 'serial_wq' finish.

Affected products

Linux kernel: from 5.4.19 before 5.5; from 5.5.3 before 5.10.235; from 5.11 before 5.15.79; from 5.16 before 6.1.129; from 6.2 before 6.6.76; from 6.7 before 6.12.13 — fixed in 5.10.235, 5.15.79, 5.5, 6.1.129, 6.12.13, 6.13.2

How to fix

Upgrade to a fixed version: Linux kernel 5.10.235, 5.15.79, 5.5, 6.1.129. Check the vendor advisory for mitigations.

References

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