CVE-2026-31715

Kernel panic via F2FS unmount race

Published May 1, 2026 · Updated May 1, 2026

Use-after-free in Linux Kernel F2FS 4.19 and later allows local users to trigger a kernel panic during filesystem unmount. The f2fs_write_end_io() callback decrements the F2FS_WB_CP_DATA page count before its warm-node check, letting concurrent f2fs_put_super() release and clear sbi->node_inode before that check dereferences it. Triggering the race requires CAP_SYS_ADMIN to mount and unmount F2FS; a successful trigger crashes the kernel rather than granting data access.

CVSS severity7.8
High
EPSS probability0.12%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in Linux Kernel F2FS 4.19 and later allows local users to trigger a kernel panic during filesystem unmount. The f2fs_write_end_io() callback decrements the F2FS_WB_CP_DATA page count before its warm-node check, letting concurrent f2fs_put_super() release and clear sbi->node_inode before that check dereferences it. Triggering the race requires CAP_SYS_ADMIN to mount and unmount F2FS; a successful trigger crashes the kernel rather than granting data access.

The record

CVE
CVE-2026-31715
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1499.004
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. May 1, 2026CVE publishedPublication date reported by the CVE source.
  2. May 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.19
  2. Affected versionversion=50fa53eccf9f911a5b435248a2b0bd484fd82e5e <188bb65f247a7a7c62f287c9a263aee3cad96fa5
  3. Affected versionversion=50fa53eccf9f911a5b435248a2b0bd484fd82e5e <2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53
  4. Affected versionversion=50fa53eccf9f911a5b435248a2b0bd484fd82e5e <963d2e24d9d92a31e6773b0f642214f10013ebf7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4.19; version=50fa53eccf9f911a5b435248a2b0bd484fd82e5e <188bb65f247a7a7c62f287c9a263aee3cad96fa5; version=50fa53eccf9f911a5b435248a2b0bd484fd82e5e <2d9c4a4ed4eef1f82c5b16b037aee8bad819fd53; version=50fa53eccf9f911a5b435248a2b0bd484fd82e5e <963d2e24d9d92a31e6773b0f642214f10013ebf7

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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