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CVE Record

CVE-2021-31916: An out-of-bounds (OOB) memory write flaw was found in list_devices in drivers/md/dm-ioctl.c in the Multi-de...

An out-of-bounds (OOB) memory write flaw was found in list_devices in drivers/md/dm-ioctl.c in the Multi-device driver module in the Linux kernel before 5.12. A bound check failure allows an attacker with special user (CAP_SYS_ADMIN) privilege to gain access to out-of-bounds memory leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to system availability.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel bug in the device-mapper control code. A local user who already has CAP_SYS_ADMIN privileges could trigger memory corruption that may crash the system or expose internal kernel information. The business concern is mainly reliability for affected Linux hosts, not remote compromise based on the supplied evidence.

Executive priority

Treat this as a moderate operational risk. It is not evidenced as remotely exploitable, but affected Linux hosts with privileged local workloads could crash or expose kernel data. Patch through standard kernel maintenance, prioritizing multi-tenant and containerized systems.

Technical view

CVE-2021-31916 is an out-of-bounds write in list_devices in drivers/md/dm-ioctl.c. The source describes a bounds-check failure in the Linux kernel before 5.12, reachable by a caller with CAP_SYS_ADMIN. Reported impacts are system crash and possible internal kernel information disclosure.

Likely exposure

Exposure is most relevant on Linux systems running affected pre-5.12 kernels where untrusted or constrained users, containers, or services may hold CAP_SYS_ADMIN. Systems without affected kernels or without such privileged local access have lower practical exposure.

Exploitation context

The supplied bundle does not show CISA KEV listing or evidence of active exploitation. Exploitation appears local and privilege-gated by CAP_SYS_ADMIN. The main cited consequence is availability loss, with possible kernel information leakage.

Researcher notes

The evidence points to a bounds-check defect in dm-ioctl list_devices fixed upstream by the referenced Linux commit. Public details in the bundle are limited: no CVSS vector, no exploit evidence, and no distribution-specific affected matrix beyond the cited advisories.

Mitigation direction

  • Apply Linux kernel updates from your distribution that include the upstream fix.
  • Review Debian LTS and vendor advisories for affected kernel packages.
  • Restrict CAP_SYS_ADMIN to only trusted workloads and administrators.
  • Prioritize hosts running containers or services with elevated Linux capabilities.
  • Check vendor guidance if using custom or backported kernels.

Validation and detection

  • Inventory Linux kernel versions across servers and images.
  • Identify hosts running Linux kernels before 5.12 or vendor-affected backports.
  • Review container and service capability grants for CAP_SYS_ADMIN.
  • Confirm installed kernel packages include the vendor security update.
  • Track remediation through vulnerability management records and reboot status.
Prepared
Confidence
medium
Sources
6

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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cwe · low confidence lookup

CWE-787: Exact CWE lookup

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cve · low confidence lookup

CVE-2021-31916 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
0Timeline events
0ADP providers
6Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/akernelKernel 5.12Listed
Weakness

CWE details

CWE-787

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

CWE-787 · source CWE mapping

Out-of-bounds Write

Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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