CVE-2025-37856

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2025-05-09. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
Trending — 4 sources updated this week
5.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.5Exploit: None knownExposed: 0

A fix is available — apply it.

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.

CVSS v3
5.5
EG Score
5.5(medium)
EG Risk
29(Track)
EG Risk 29/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity55% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
18%
KEV
Not listed

Published

May 9, 2025

Last Modified

August 5, 2026

Advisory Details (4)

Auto-updated Aug 2, 2026
No patch confirmed yet.
generic

btrfs: harden block_group::bg_list against list_del() races - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/bf089c4d1141b27332c092b1dcca5022c415a3b6
generic

btrfs: harden block_group::bg_list against list_del() races - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/909e60fb469d4101c6b08cf6e622efb062bb24a1
generic

btrfs: harden block_group::bg_list against list_del() races - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/7511e29cf1355b2c47d0effb39e463119913e2f6
generic

btrfs: harden block_group::bg_list against list_del() races - kernel/git/stable/linux.git - Linux kernel stable tree

https://git.kernel.org/stable/c/185fd73e5ac06027c4be9a129e59193f6a3ef202

Vendor Advisories for CVE-2025-37856(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(20)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-virtual-hwe-24.04-edge (6.14.0-22.22) @ plucky2026-05-30ubuntu
ubuntulinux-virtual-6.8 (6.8.0-100.100) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure (6.14.0-1007.7) @ plucky2026-05-30ubuntu
ubuntulinux-tools-oracle-64k (6.14.0-1007.7) @ plucky2026-05-30ubuntu
ubuntulinux-tools-realtime-hwe-22.04 (6.8.1-1041.42~22.04.1) @ jammy2026-05-30ubuntu
ubuntulinux-tools-gcp-edge (6.8.0-1047.50~22.04.2) @ jammy2026-05-30ubuntu
ubuntulinux-tools-realtime-6.8.1 (6.8.1-1041.42) @ noble2026-05-30ubuntu
ubuntulinux-tools-fips-6.8 (6.8.0-100.100+fips1) @ noble2026-05-30ubuntu
ubuntulinux-tools-gcp-fips-6.8 (6.8.0-1047.50+fips1) @ noble2026-05-30ubuntu
ubuntulinux-tools-oracle-lts-24.04 (6.8.0-1043.44) @ noble2026-05-30ubuntu
ubuntulinux-virtual-hwe-22.04-edge (6.8.0-100.100~22.04.1) @ jammy2026-05-30ubuntu
ubuntulinux-tools-gke-64k-6.8 (6.8.0-1043.48) @ noble2026-05-30ubuntu
ubuntulinux-tools-lowlatency-hwe-20.04-edge (6.8.0-100.100.1) @ noble2026-05-30ubuntu
ubuntulinux-xilinx-zynqmp (6.8.0.1023.24) @ noble2026-05-30ubuntu
ubuntulinux-tools-nvidia-lowlatency-64k-6.8 (6.8.0-1046.49.1) @ noble2026-05-30ubuntu
ubuntulinux-tools-ibm-lts-24.04 (6.8.0-1044.44) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-lts-24.04 (6.8.0-1046.52) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-fips-6.8 (6.8.0-1046.52+fips1) @ noble2026-05-30ubuntu
ubuntulinux-tools-azure-edge (6.8.0-1051.57~22.04.1) @ jammy2026-05-30ubuntu
linuxKernel @ 6.12.24—osv

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Additional Vendor Advisories

(19)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 45× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 111 total refreshes for this CVE.

  1. 2026-08-07 16:26 UTCEPSS rescore
  2. 2026-08-06 13:46 UTCEPSS rescore
  3. 2026-08-05 13:56 UTCEG score recompute
  4. 2026-08-05 13:56 UTCVendor advisory
  5. 2026-08-05 13:56 UTCGHSA enrichment
  6. 2026-08-04 15:09 UTCEPSS rescore
  7. 2026-08-04 10:37 UTCEPSS rescore
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  10. 2026-08-01 04:15 UTCEPSS rescore
  11. 2026-07-30 16:27 UTCEPSS rescore
  12. 2026-07-30 07:11 UTCEG score recompute
  13. 2026-07-30 07:11 UTCVendor advisory
  14. 2026-07-30 07:11 UTCGHSA enrichment
  15. 2026-07-30 01:29 UTCEPSS rescore
  16. 2026-07-28 15:35 UTCEPSS rescore
  17. 2026-07-26 14:54 UTCEPSS rescore
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  20. 2026-07-24 14:17 UTCEPSS rescore
  21. 2026-07-24 06:41 UTCOSV refresh
  22. 2026-07-23 02:54 UTCEG score recompute
  23. 2026-07-22 14:07 UTCEPSS rescore
  24. 2026-07-22 14:07 UTCEPSS rescore
  25. 2026-07-21 15:24 UTCEPSS rescore
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  1. 2026-07-20 17:07 UTCEPSS rescore
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  19. 2026-07-09 19:09 UTCEPSS rescore
  20. 2026-07-09 19:09 UTCEPSS rescore
  21. 2026-07-07 13:45 UTCEPSS rescore
  22. 2026-07-07 02:21 UTCOSV refresh
  23. 2026-07-06 16:27 UTCEPSS rescore
  24. 2026-07-06 16:27 UTCEPSS rescore
  25. 2026-07-06 02:23 UTCEPSS rescore
  26. 2026-07-05 02:30 UTCEPSS rescore
  27. 2026-07-04 06:30 UTCEPSS rescore
  28. 2026-07-01 15:06 UTCEPSS rescore
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  30. 2026-06-30 23:22 UTCEPSS rescore
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  40. 2026-06-25 13:49 UTCEPSS rescore
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  44. 2026-06-23 21:32 UTCEPSS rescore
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  46. 2026-06-22 14:25 UTCEPSS rescore
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  48. 2026-06-21 14:56 UTCEPSS rescore
  49. 2026-06-21 14:56 UTCEPSS rescore
  50. 2026-06-21 01:59 UTCEPSS rescore
  51. 2026-06-21 01:59 UTCEPSS rescore
  52. 2026-06-19 19:25 UTCEPSS rescore
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  54. 2026-06-18 17:52 UTCEPSS rescore
  55. 2026-06-18 17:52 UTCEPSS rescore
  56. 2026-06-18 13:13 UTCOSV refresh
  57. 2026-06-17 17:52 UTCEPSS rescore
  58. 2026-06-16 17:52 UTCEPSS rescore
  59. 2026-06-16 17:52 UTCEPSS rescore
  60. 2026-06-14 23:17 UTCEPSS rescore
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  66. 2026-06-08 14:16 UTCEPSS rescore
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  68. 2026-06-07 15:24 UTCEPSS rescore
  69. 2026-06-06 13:47 UTCEPSS rescore
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  73. 2026-06-05 06:10 UTCEPSS rescore
  74. 2026-06-05 06:10 UTCEPSS rescore
  75. 2026-06-04 13:12 UTCEPSS rescore

Related CVEs(same product + same vendor)

Frequently asked(5)

What is CVE-2025-37856?
CVE-2025-37856 is a medium vulnerability published on May 9, 2025. In the Linux kernel, the following vulnerability has been resolved: btrfs: harden blockgroup::bglist against list_del() races As far as I can tell, these calls of listdelinit() on bg_list cannot run concurrently with btrfsmarkbgunused() or btrfsmarkbgto_reclaim(), as they are in transaction error…
When was CVE-2025-37856 disclosed?
CVE-2025-37856 was first published in the National Vulnerability Database on May 9, 2025, with the most recent update on August 5, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-37856 actively exploited?
CVE-2025-37856 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 82.1% of all scored CVEs.
What is the CVSS score of CVE-2025-37856?
CVE-2025-37856 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2025-37856?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-37856, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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