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

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.

Published: 2025-02-27 Last update: 2026-05-12 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-21726 is rated Low Risk (33.4/100): CVSS High severity, with low exploitation likelihood (EPSS 0.04%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-21726

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-11-20 0.05% 0.04% -0.02%
2 2025-11-18 0.04% 0.05% +0.01%
3 2025-02-27 — 0.04% —

Full EPSS history (3 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21726

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.8 3.1 HIGH
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 5.9 134c704f-9b21-4f2e-91b3-4a467353bcc0

Weakness enumeration for CVE-2025-21726

GitHub Security Advisory for CVE-2025-21726

GHSA-4gxw-5w55-6f5h · Severity: high — In the Linux kernel, the following vulnerability has been resolved: padata: avoid UAF for...

OS Trackers for CVE-2025-21726

vendor priority summary link
debian not yet assigned CVE-2025-21726 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2025-21726
redhat medium — https://access.redhat.com/security/cve/CVE-2025-21726
suse high — https://www.suse.com/security/cve/CVE-2025-21726/
ubuntu high CVE-2025-21726 high priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, released 189, ignored 148, not-affected 67, needed 1, pending 1. https://ubuntu.com/security/CVE-2025-21726

Affected software / configurations for CVE-2025-21726

Vendor Product Version Raw CPE
linux linux_kernel >= 5.4.19, < 5.5 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.5.3, < 5.10.235 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.11, < 5.15.79 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 5.16, < 6.1.129 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.76 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.13 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.13.2 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

References for CVE-2025-21726

cvelogic Threat Intelligence