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CVE-2021-4149

21
FAUCET Score

CVE-2021-4149 describes a denial-of-service vulnerability in the Linux kernel's btrfs filesystem, specifically within the btrfs_alloc_tree_b function, affecting Debian and other Linux distributions. This flaw, rated Medium severity (CVSS 5.5), allows a local attacker with low privileges to cause a system deadlock due to an improper lock operation. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.15CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
5.15CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:5.15:-:*:*:*:*:*:*
5.15CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:5.15:rc1:*:*:*:*:*:*
5.15CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:5.15:rc2:*:*:*:*:*:*
5.15CPE matchmatch criteria
cpe:2.3:o:linux:linux_kernel:5.15:rc3:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.5MEDIUM

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.40%
Probability of exploitation in next 30 days
EPSS Percentile
32.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0040 is in the 88th percentile among its peer group of 15,940 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

microsoftpatch availablevia msrc
Product: 18454-16820Fixed in: -
microsoftpatch availablevia msrc
Product: cm1 kernel 5.10.111.1-1 on CBL Mariner 1.0Fixed in: -

Vendor Advisories (2)

microsoft2022-Mar/CVE-2021-4149Moderate

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.

Mar 8, 2022
redhatCVE-2021-4149Moderate

kernel: Improper lock operation in btrfs

Oct 18, 2021

References

bugzilla.redhat.com / show_bug.cgi
Issue TrackingThird Party Advisory
lists.debian.org / debian-lts-announce/2022/07/msg00000.html
Mailing ListThird Party Advisory
lkml.org / lkml/2021/10/18/885
ExploitMailing ListPatchThird Party Advisory
lkml.org / lkml/2021/9/13/2565
ExploitMailing ListThird Party Advisory