CVE-2021-4149

MEDIUMNVD 5.55.5—
EchelonGraph scoreMEDIUM confidence

Score 5.5 from GitHub Security Advisory published 2022-03-24. NVD baseline CVSS 5.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
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.

A vulnerability was found in btrfs_alloc_tree_b in fs/btrfs/extent-tree.c in the Linux kernel due to an improper lock operation in btrfs. In this flaw, a user with a local privilege may cause a denial of service (DOS) due to a deadlock problem.

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
33%
KEV
Not listed

Published

March 23, 2022

Last Modified

November 21, 2024

References (8)

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulinux-tools-aws-hwe (4.15.0.1133.122) @ xenial2026-05-26ubuntu
ubuntulinux-tools-4.4.0-239-lowlatency (4.4.0-239.273) @ xenial2026-05-26ubuntu
ubuntulinux-tools-4.4.0-1155-aws (4.4.0-1155.170) @ xenial2026-05-26ubuntu
ubuntulinux-image-4.4.0-1117-aws (4.4.0-1117.123) @ trusty2026-05-26ubuntu

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.

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(5)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 10× in last 7d / 46× 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 107 total refreshes for this CVE.

  1. 2026-07-26 14:52 UTCEPSS rescore
  2. 2026-07-25 14:15 UTCEPSS rescore
  3. 2026-07-24 14:15 UTCEPSS rescore
  4. 2026-07-24 14:15 UTCEPSS rescore
  5. 2026-07-23 02:04 UTCEG score recompute
  6. 2026-07-22 22:51 UTCEG score recompute
  7. 2026-07-22 14:06 UTCEPSS rescore
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  15. 2026-07-17 19:29 UTCOSV refresh
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  1. 2026-07-09 19:07 UTCEPSS rescore
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  14. 2026-07-01 15:04 UTCEPSS rescore
  15. 2026-06-30 23:20 UTCEPSS rescore
  16. 2026-06-29 17:23 UTCOSV refresh
  17. 2026-06-29 14:04 UTCEPSS rescore
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  22. 2026-06-27 03:07 UTCEPSS rescore
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  24. 2026-06-25 13:48 UTCEPSS rescore
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  26. 2026-06-24 14:03 UTCEPSS rescore
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  31. 2026-06-21 14:55 UTCEPSS rescore
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  44. 2026-06-13 22:58 UTCEPSS rescore
  45. 2026-06-13 22:58 UTCEPSS rescore
  46. 2026-06-12 23:10 UTCEPSS rescore
  47. 2026-06-12 06:06 UTCOSV refresh
  48. 2026-06-11 13:58 UTCEPSS rescore
  49. 2026-06-10 22:16 UTCEPSS rescore
  50. 2026-06-10 13:20 UTCEPSS rescore
  51. 2026-06-08 14:15 UTCEPSS rescore
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  54. 2026-06-07 15:23 UTCEPSS rescore
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  56. 2026-06-06 13:46 UTCEPSS rescore
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  68. 2026-05-31 22:29 UTCEPSS rescore
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  71. 2026-05-29 13:42 UTCEPSS rescore
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  74. 2026-05-27 13:39 UTCEPSS rescore
  75. 2026-05-27 13:39 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2021-4149?
CVE-2021-4149 is a medium vulnerability published on March 23, 2022. A vulnerability was found in btrfsalloctree_b in fs/btrfs/extent-tree.c in the Linux kernel due to an improper lock operation in btrfs. In this flaw, a user with a local privilege may cause a denial of service (DOS) due to a deadlock problem.
When was CVE-2021-4149 disclosed?
CVE-2021-4149 was first published in the National Vulnerability Database on March 23, 2022, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2021-4149 actively exploited?
CVE-2021-4149 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 67.3% of all scored CVEs.
What is the CVSS score of CVE-2021-4149?
CVE-2021-4149 has a CVSS v3 base score of 5.5 (NVD).
How do I remediate CVE-2021-4149?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2021-4149, 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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