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CVE Record

CVE-2021-46945: ext4: always panic when errors=panic is specified

In the Linux kernel, the following vulnerability has been resolved: ext4: always panic when errors=panic is specified Before commit 014c9caa29d3 ("ext4: make ext4_abort() use __ext4_error()"), the following series of commands would trigger a panic: 1. mount /dev/sda -o ro,errors=panic test 2. mount /dev/sda -o remount,abort test After commit 014c9caa29d3, remounting a file system using the test mount option "abort" will no longer trigger a panic. This commit will restore the behaviour immediately before commit 014c9caa29d3. (However, note that the Linux kernel's behavior has not been consistent; some previous kernel versions, including 5.4 and 4.19 similarly did not panic after using the mount option "abort".) This also makes a change to long-standing behaviour; namely, the following series commands will now cause a panic, when previously it did not: 1. mount /dev/sda -o ro,errors=panic test 2. echo test > /sys/fs/ext4/sda/trigger_fs_error However, this makes ext4's behaviour much more consistent, so this is a good thing.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This Linux ext4 issue is about inconsistent enforcement of the errors=panic filesystem setting. In affected kernels, some ext4 error paths did not panic the system even when that policy was configured. Business urgency is generally low unless your operations deliberately rely on errors=panic for fail-stop behavior on storage errors.

Executive priority

Treat this as a targeted reliability and operational-control issue, not a broad internet-facing emergency. Patch through normal kernel maintenance, with faster handling for systems where ext4 panic behavior is part of safety, clustering, or data-protection assumptions.

Technical view

The kernel fix restores and broadens ext4 behavior so configured errors=panic paths consistently call panic on abort or triggered filesystem error conditions. The CVE data identifies affected Linux kernel releases around 5.11 through 5.13, but no CVSS, CWE, or distribution-specific package mapping is provided.

Likely exposure

Exposure is limited to Linux systems using ext4 where errors=panic is configured or tested. Practical relevance is highest for appliances, HA nodes, storage-sensitive systems, or operational controls that depend on a kernel panic after ext4 errors.

Exploitation context

The provided sources do not show active exploitation, and KEV is false. The described conditions involve mount/remount behavior and ext4 error triggers, which generally imply local administrative control or deliberate operational testing rather than remote exploitation.

Researcher notes

Evidence is sparse: the bundle provides the kernel commit rationale and affected release hints, but no CVSS, CWE, exploit reports, or distro package ranges. Avoid over-scoping impact beyond ext4 errors=panic behavior unless vendor advisories add product-specific context.

Mitigation direction

  • Check vendor kernel advisories for fixed packages for affected Linux distributions.
  • Prioritize systems using ext4 with errors=panic in production or HA designs.
  • Apply kernel updates that include the referenced stable ext4 fixes.
  • Review operational reliance on fail-stop behavior after ext4 errors.

Validation and detection

  • Inventory Linux kernel versions against vendor advisories and CVE-2021-46945 status.
  • Identify ext4 mounts configured with errors=panic.
  • Confirm deployed kernels include one of the referenced stable fixes.
  • Document whether panic-on-error behavior is required for each affected system.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2021-46945 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux014c9caa29d3a44e0de695c99ef18bec3e887d52, 014c9caa29d3a44e0de695c99ef18bec3e887d52, 014c9caa29d3a44e0de695c99ef18bec3e887d52unaffected
LinuxLinux5.11, 0, 5.11.20, 5.12.3, 5.13affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.