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Fencer Vulns
high 7.8

CVE-2025-38627 json

f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic

published 2025-08-22 14 mo ago modified 2026-08-05 3 mo ago also EUVD-2025-25574

cvss
7.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits
0
none known

Summary

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

f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic

The decompress_io_ctx may be released asynchronously after I/O completion. If this file is deleted immediately after read, and the kworker of processing post_read_wq has not been executed yet due to high workloads, It is possible that the inode(f2fs_inode_info) is evicted and freed before it is used f2fs_free_dic.

The UAF case as below: Thread A Thread B - f2fs_decompress_end_io - f2fs_put_dic - queue_work add free_dic work to post_read_wq - do_unlink - iput - evict - call_rcu This file is deleted after read.

Thread C kworker to process post_read_wq - rcu_do_batch - f2fs_free_inode - kmem_cache_free inode is freed by rcu - process_scheduled_works - f2fs_late_free_dic - f2fs_free_dic - f2fs_release_decomp_mem read (dic->inode)->i_compress_algorithm

This patch store compress_algorithm and sbi in dic to avoid inode UAF.

In addition, the previous solution is deprecated in [1] may cause system hang. [1] https://lore.kernel.org/all/c36ab955-c8db-4a8b-a9d0-f07b5f426c3f@kernel.org

Patch / fix

  • Linux Linux 6.1.175, 6.6.118, 6.12.78, 6.16.1, 6.17
  • linux Debian 12 6.1.176-1
  • linux Debian 13 6.12.85-1
  • linux Debian 14 6.16.3-1

debian advisories DEBIAN-CVE-2025-38627

  • linux Ubuntu 24.04 LTS 6.8.0-106.106
  • linux-aws Ubuntu 24.04 LTS 6.8.0-1050.53
  • linux-gcp Ubuntu 24.04 LTS 6.8.0-1052.55
  • linux-gke Ubuntu 24.04 LTS 6.8.0-1048.53
  • linux-ibm Ubuntu 24.04 LTS 6.8.0-1049.49
  • linux-azure Ubuntu 24.04 LTS 6.8.0-1051.57
  • linux-gkeop Ubuntu 24.04 LTS 6.8.0-1035.38
  • linux-raspi Ubuntu 24.04 LTS 6.8.0-1050.54

ubuntu advisories UBUNTU-CVE-2025-38627

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel Azure Linux 3.0 6.6.119.3-1

azure linux advisories AZL-66602

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-38627 updated

kernel: f2fs: compress: fix UAF of f2fs_inode_info in f2fs_free_dic

  • Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernel
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 7.8 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

  • Linux Linux

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.