CVE-2026-31702

Kernel-memory corruption via compressed-writeback unmount race

Published May 1, 2026 · Updated May 1, 2026

Use-after-free in Linux Kernel allows local users to corrupt kernel memory through an f2fs compressed-writeback and unmount race. f2fs_compress_write_end_io decrements F2FS_WB_CP_DATA before its final sbi access, letting concurrent unmount destroy page_array_slab before page_array_free dereferences it. The race requires compressed f2fs writeback to complete during unmount; resulting corruption can disclose or alter kernel memory or crash the system.

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 allows local users to corrupt kernel memory through an f2fs compressed-writeback and unmount race. f2fs_compress_write_end_io decrements F2FS_WB_CP_DATA before its final sbi access, letting concurrent unmount destroy page_array_slab before page_array_free dereferences it. The race requires compressed f2fs writeback to complete during unmount; resulting corruption can disclose or alter kernel memory or crash the system.

The record

CVE
CVE-2026-31702
Published
May 1, 2026
Updated
May 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-416, T1068
Attack vector
local
Privileges
authenticated

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

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Is a vulnerable build present?

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

  1. Affected versionversion=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <2c97dcb6147c8f7f25c629b93be1e69617de5d4a
  2. Affected versionversion=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <39d4ee19c1e7d753dd655aebee632271b171f43a
  3. Affected versionversion=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <c76cf339b87975ae5b2c06d2d774d5667d25a12a
  4. Affected versionversion=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <ef57cd3329b40c739b9a2e1a8a21ecc4171c6280
  5. Affected versionversion=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <f5154cf3ce1c8193f0c1891d3769f62740cfe6fe
  6. Affected versionversion=5.6

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <2c97dcb6147c8f7f25c629b93be1e69617de5d4a; version=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <39d4ee19c1e7d753dd655aebee632271b171f43a; version=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <c76cf339b87975ae5b2c06d2d774d5667d25a12a; version=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <ef57cd3329b40c739b9a2e1a8a21ecc4171c6280; version=4c8ff7095bef64fc47e996a938f7d57f9e077da3 <f5154cf3ce1c8193f0c1891d3769f62740cfe6fe; version=5.6

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-416Use After Free
T1068Exploitation for Privilege Escalation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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