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Vulnerabilities

Vulnerability · CVE-2025-37856

In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init()

Published May 9, 2025 · catalog updated Oct 21, 2026 · linux kernel

Check if you run it

No confirmed exploitation is on record for CVE-2025-37856. EPSS is 0.28%. Act only if a listed version of linux kernel is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.28%
Remediation
Version ranges on file
Affected products
cpe linux/linux kernel · vendor Linux Linux a9f189716cf15913c453299d72f69c51a9b0f86b <bf089c4d1141b27332c092b1dcca5022c415a3b6

In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at all of racing with mark_bg_unused(), or a different future user of bg_list, better to be safe than sorry. Otherwise we risk the following interleaving (bg_list refcount in parens) T1 (some random op) T2 (btrfs_mark_bg_unused) !list_empty(&bg->bg_list); (1) list_del_init(&bg->bg_list); (1) list_move_tail (1) btrfs_put_block_group (0) btrfs_delete_unused_bgs bg = list_first_entry list_del_init(&bg->bg_list); btrfs_put_block_group(bg); (-1) Ultimately, this results in a broken ref count that hits zero one deref early and the real final deref underflows the refcount, resulting in a WARNING.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe linux/linux kernel< 6.12.24
  • cpe linux/linux kernel< 6.13.12
  • cpe linux/linux kernel< 6.14.3
  • vendor Linux Linux a9f189716cf15913c453299d72f69c51a9b0f86b <bf089c4d1141b27332c092b1dcca5022c415a3b6a9f189716cf15913c453299d72f69c51a9b0f86b <bf089c4d1141b27332c092b1dcca5022c415a3b6

How to fix CVE-2025-37856

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-37856. EPSS is 0.28%. Act only if a listed version of linux kernel is installed.

Which versions are affected?

Compare what you have installed with linux/linux kernel < 6.12.24; linux/linux kernel < 6.13.12; linux/linux kernel < 6.14.3; Linux Linux a9f189716cf15913c453299d72f69c51a9b0f86b <bf089c4d1141b27332c092b1dcca5022c415a3b6 a9f189716cf15913c453299d72f69c51a9b0f86b <bf089c4d1141b27332c092b1dcca5022c415a3b6. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.28%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. May 9, 2025 · EUVD

    Detected

    In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at a

  2. Aug 5, 2026 · EUVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at a

  3. Oct 21, 2026 · NIST NVD

    Updated

    In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as they are in transaction error paths and situations where the block group is readonly. However, if there is any chance at a

Sources

  • CVE.orgVulnerability recordCVE-2025-37856

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-37856

    30-day exploitation probability 0.28%

    first.org
  • EUVDVulnerability recordEUVD-2025-14136

    In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as th

    euvd.enisa.europa.eu
  • NIST NVDVulnerability recordCVE-2025-37856

    In the Linux kernel, the following vulnerability has been resolved: btrfs: harden block_group::bg_list against list_del() races As far as I can tell, these calls of list_del_init() on bg_list cannot run concurrently with btrfs_mark_bg_unused() or btrfs_mark_bg_to_reclaim(), as

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 21, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.