Description
In the Linux kernel, the following vulnerability has been resolved:

erofs: fix use-after-free on sbi->sync_decompress

z_erofs_decompress_kickoff() can race with filesystem unmount, causing
a use-after-free on sbi->sync_decompress.

When I/O completes, z_erofs_endio() calls z_erofs_decompress_kickoff()
to queue z_erofs_decompressqueue_work() asynchronously. Then, after all
folios are unlocked, unmount workflow can proceed and sbi will be freed
before accessing to sbi->sync_decompress.

Thread (unmount) I/O completion kworker
queue_work
z_erofs_decompressqueue_work
(all folios are unlocked)
cleanup_mnt
..
erofs_kill_sb
erofs_sb_free
kfree(sbi)
access sbi->sync_decompress // UAF!!
Published: 2026-06-25
Score: 7.8 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

A race condition occurs when the erofs decompression routine is scheduled to run after the file system is unmounted, causing a use‑after‑free of the superblock structure (sbi->sync_decompress). The memory corruption that results can be exploited by an attacker to gain arbitrary execution in kernel space, leading to privilege escalation or a system crash.

Affected Systems

All Linux kernel configurations that compile with erofs support are potentially affected. Any release containing the erofs module prior to the commit that introduced the fix is vulnerable. The vulnerability is active only on systems that mount an erofs file system and expose the ability to unmount it.

Risk and Exploitability

The CVSS score of 7.8 indicates a high risk, while the EPSS score of < 1% suggests that exploitation, if attempted, is unlikely to be widely observed. The vulnerability is not listed in the CISA KEV catalog at this time. The likely attack vector is a local entity that can trigger an unmount on an erofs file system; based on the description, it is inferred that the attacker must have permission to unmount the file system, typically root or a user with remount capabilities. If such an attacker can cause the unmount sequence to proceed while z_erofs_decompress_kickoff() is still queued, the use‑after‑free can be triggered, leading to kernel memory corruption. No public exploit has been reported yet.

Generated by OpenCVE AI on August 13, 2026 at 18:28 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Update the Linux kernel to a release that includes the erofs use‑after‑free patch, or apply the patch from the kernel commit references listed.
  • If an immediate kernel upgrade is not possible, rebuild the kernel with erofs support disabled or mount all erofs file systems in read‑only mode before launch to reduce the race window.
  • Ensure that all erofs file systems are unmounted cleanly before shutdown or reboot; consider adding a step in shutdown scripts to unmount or remount read‑only to prevent the race condition.

Generated by OpenCVE AI on August 13, 2026 at 18:28 UTC.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Thu, 13 Aug 2026 13:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-362

Tue, 30 Jun 2026 03:45:00 +0000

Type Values Removed Values Added
Weaknesses CWE-362

Tue, 30 Jun 2026 02:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Tue, 30 Jun 2026 00:45:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

threat_severity

Moderate


Thu, 25 Jun 2026 12:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Thu, 25 Jun 2026 09:15:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: erofs: fix use-after-free on sbi->sync_decompress z_erofs_decompress_kickoff() can race with filesystem unmount, causing a use-after-free on sbi->sync_decompress. When I/O completes, z_erofs_endio() calls z_erofs_decompress_kickoff() to queue z_erofs_decompressqueue_work() asynchronously. Then, after all folios are unlocked, unmount workflow can proceed and sbi will be freed before accessing to sbi->sync_decompress. Thread (unmount) I/O completion kworker queue_work z_erofs_decompressqueue_work (all folios are unlocked) cleanup_mnt .. erofs_kill_sb erofs_sb_free kfree(sbi) access sbi->sync_decompress // UAF!!
Title erofs: fix use-after-free on sbi->sync_decompress
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-06-25T08:39:57.147Z

Reserved: 2026-06-09T07:44:35.395Z

Link: CVE-2026-53272

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2026-06-25T09:16:45.353

Modified: 2026-07-08T04:01:32.377

Link: CVE-2026-53272

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-06-25T00:00:00Z

Links: CVE-2026-53272 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-08-13T18:30:16Z

Weaknesses