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CVE Record

CVE-2021-46950: md/raid1: properly indicate failure when ending a failed write request

In the Linux kernel, the following vulnerability has been resolved: md/raid1: properly indicate failure when ending a failed write request This patch addresses a data corruption bug in raid1 arrays using bitmaps. Without this fix, the bitmap bits for the failed I/O end up being cleared. Since we are in the failure leg of raid1_end_write_request, the request either needs to be retried (R1BIO_WriteError) or failed (R1BIO_Degraded).

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-46950 is a Linux kernel md/raid1 data-corruption flaw. On RAID1 arrays using bitmaps, a failed write could incorrectly clear bitmap state, making the system treat failed I/O as handled. The main business risk is silent or delayed storage inconsistency on affected Linux hosts, not remote takeover.

Executive priority

Treat this as high priority for systems where Linux md RAID1 protects critical data. It is not evidenced as actively exploited, but storage corruption can create business outage and recovery risk. Patch affected kernels through normal vendor channels and verify backups before maintenance.

Technical view

The flaw is in md/raid1 write completion handling. In the failed-write path, bitmap bits for failed I/O could be cleared unless the request was properly marked for retry or degraded failure. The CVE metadata rates it CVSS 7.8: local, low-complexity, low-privilege, with high confidentiality, integrity, and availability impact.

Likely exposure

Exposure is likely on Linux systems using md RAID1 arrays with bitmaps and affected kernel versions listed in the CVE metadata, including 4.14.233, 4.19.191, 5.4.118, 5.10.36, 5.11.20, 5.12.3, and 5.13. Systems not using md/raid1 bitmaps are less likely exposed based on the provided evidence.

Exploitation context

The CVE is not listed as KEV, and the provided sources do not claim active exploitation. The attack vector is local with low privileges. Practical concern centers on triggering or encountering failed write behavior that can cause data corruption, rather than a remotely exploitable service vulnerability.

Researcher notes

Evidence supports a kernel logic flaw in raid1_end_write_request handling for failed writes with bitmaps. The public bundle provides stable kernel commits but no exploit report, no KEV status, and no affected distribution matrix. Avoid assuming all Linux systems are affected; exposure depends on md/raid1 bitmap use and kernel backport status.

Mitigation direction

  • Inventory Linux hosts using md/raid1 arrays with bitmaps.
  • Prioritize storage, database, virtualization, backup, and file-service hosts.
  • Apply vendor-supported kernel updates containing the referenced stable fixes.
  • If patch timing is unclear, check distribution advisories for backported fixes.
  • Review backup integrity and recovery readiness for affected storage systems.

Validation and detection

  • Check running kernel versions against vendor advisories and CVE metadata.
  • Identify md RAID1 arrays and whether write-intent bitmaps are enabled.
  • Confirm installed kernel includes the relevant stable fix or distribution backport.
  • Review storage logs for RAID degradation, write errors, or bitmap-related anomalies.
  • Validate backups for critical systems before and after remediation.
Prepared
Confidence
high
Sources
9

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-2021-46950 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

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.

1CVSS vectors
3Timeline events
2ADP providers
8Source links

SSVC decision data

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

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2021-46950Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux900c531899f5ee2321bef79e20055787bc73251d, 1cd972e0a10760a1fa27d9830d78446c891c23b6, eeba6809d8d58908b5ed1b5ceb5fcb09a98a7cad, eeba6809d8d58908b5ed1b5ceb5fcb09a98a7cad, eeba6809d8d58908b5ed1b5ceb5fcb09a98a7cad, eeba6809d8d58908b5ed1b5ceb5fcb09a98a7cad, eeba6809d8d58908b5ed1b5ceb5fcb09a98a7cad, a1f4fcb880988a96c0b2d5c3305ffc4e49eca0ed, 344242d50f468a250bf4b6136934392758412ed8unaffected
LinuxLinux5.4, 0, 4.14.233, 4.19.191, 5.4.118, 5.10.36, 5.11.20, 5.12.3, 5.13affected
Weakness

CWE details

No CWE listed

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