CVE-2021-47145

System crash via fatal Btrfs error assertion

Published Mar 25, 2024 · Updated May 11, 2026

Reachable assertion in the Linux kernel Btrfs implementation allows local users to crash the system during filesystem log replay. In link_to_fixup_dir, a BUG_ON treats any negative return from btrfs_search_slot, including legitimate -EIO and other errors, as a fatal kernel condition instead of returning the error. The path requires local access and a Btrfs mount that replays a log and encounters such a search error; the resulting kernel panic interrupts the host.

CVSS severity5.5
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reachable assertion in the Linux kernel Btrfs implementation allows local users to crash the system during filesystem log replay. In link_to_fixup_dir, a BUG_ON treats any negative return from btrfs_search_slot, including legitimate -EIO and other errors, as a fatal kernel condition instead of returning the error. The path requires local access and a Btrfs mount that replays a log and encounters such a search error; the resulting kernel panic interrupts the host.

The record

CVE
CVE-2021-47145
Published
Mar 25, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 25, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.29
  2. Affected versionversion=e02119d5a7b4396c5a872582fddc8bd6d305a70a <0eaf383c6a4a83c09f60fd07a1bea9f1a9181611
  3. Affected versionversion=e02119d5a7b4396c5a872582fddc8bd6d305a70a <0ed102453aa1cd12fefde8f6b60b9519b0b1f003
  4. Affected versionversion=e02119d5a7b4396c5a872582fddc8bd6d305a70a <6eccfb28f8dca70c9b1b3bb3194ca54cbe73a9fa
  5. Affected versionversion=e02119d5a7b4396c5a872582fddc8bd6d305a70a <76bfd8ac20bebeae599452a03dfc5724c0475dcf
  6. Affected versionversion=e02119d5a7b4396c5a872582fddc8bd6d305a70a <7e13db503918820e6333811cdc6f151dcea5090a
  7. Affected versionversion=e02119d5a7b4396c5a872582fddc8bd6d305a70a <91df99a6eb50d5a1bc70fff4a09a0b7ae6aab96d
  8. Affected versionversion=e02119d5a7b4396c5a872582fddc8bd6d305a70a <b545442133580dcb2f2496133bf850824d41255c
  9. Affected versionversion=e02119d5a7b4396c5a872582fddc8bd6d305a70a <e934c4ee17b33bafb0444f2f9766cda7166d3c40

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.29; version=e02119d5a7b4396c5a872582fddc8bd6d305a70a <0eaf383c6a4a83c09f60fd07a1bea9f1a9181611; version=e02119d5a7b4396c5a872582fddc8bd6d305a70a <0ed102453aa1cd12fefde8f6b60b9519b0b1f003; version=e02119d5a7b4396c5a872582fddc8bd6d305a70a <6eccfb28f8dca70c9b1b3bb3194ca54cbe73a9fa; version=e02119d5a7b4396c5a872582fddc8bd6d305a70a <76bfd8ac20bebeae599452a03dfc5724c0475dcf; version=e02119d5a7b4396c5a872582fddc8bd6d305a70a <7e13db503918820e6333811cdc6f151dcea5090a; version=e02119d5a7b4396c5a872582fddc8bd6d305a70a <91df99a6eb50d5a1bc70fff4a09a0b7ae6aab96d; version=e02119d5a7b4396c5a872582fddc8bd6d305a70a <b545442133580dcb2f2496133bf850824d41255c; version=e02119d5a7b4396c5a872582fddc8bd6d305a70a <e934c4ee17b33bafb0444f2f9766cda7166d3c40

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499Endpoint Denial of Service

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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