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CVE Record

CVE-2019-19813: In the Linux kernel 5.0.21, mounting a crafted btrfs filesystem image, performing some operations, and then...

In the Linux kernel 5.0.21, mounting a crafted btrfs filesystem image, performing some operations, and then making a syncfs system call can lead to a use-after-free in __mutex_lock in kernel/locking/mutex.c. This is related to mutex_can_spin_on_owner in kernel/locking/mutex.c, __btrfs_qgroup_free_meta in fs/btrfs/qgroup.c, and btrfs_insert_delayed_items in fs/btrfs/delayed-inode.c.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2019-19813 is a Linux kernel Btrfs issue where a crafted filesystem image can trigger a kernel use-after-free after mounting and later filesystem activity. The public record does not provide CVSS scoring or broad affected-product details. Treat it as most relevant to systems that mount Btrfs images, especially untrusted or user-supplied media.

Executive priority

Prioritize remediation where Linux systems process disk images, removable media, or user-controlled filesystem content. For standard servers with no Btrfs use and no untrusted mounts, urgency is lower. Because scoring and affected-version details are incomplete, rely on vendor package status before making closure decisions.

Technical view

The CVE describes a use-after-free in __mutex_lock within Linux kernel 5.0.21, related to Btrfs quota-group metadata freeing and delayed inode insertion paths. Triggering requires mounting a crafted Btrfs filesystem image, performing operations, and invoking syncfs. Public sources identify vendor advisories but do not provide a complete affected-version matrix here.

Likely exposure

Exposure is most likely on Linux systems that support Btrfs and allow mounting crafted or untrusted filesystem images. Servers, appliances, forensic workstations, CI workers, and desktop endpoints handling disk images deserve review. The bundle does not establish exposure for all Linux distributions or versions.

Exploitation context

The source bundle does not show CISA KEV listing or confirmed active exploitation. A public GitHub reference exists, indicating public research material, but the provided evidence does not justify claiming real-world exploitation. The described trigger has local or operational prerequisites because a crafted Btrfs image must be mounted.

Researcher notes

The strongest technical signal is the CVE description: Linux 5.0.21, Btrfs, crafted image, syncfs, and use-after-free in mutex/Btrfs paths. The bundle lacks CVSS, CWE, complete affected versions, and exploit confirmation. Vendor advisories should be used to map fixed package versions and platform-specific impact.

Mitigation direction

  • Apply vendor kernel updates that address CVE-2019-19813 where available.
  • Check Linux distribution and appliance advisories for affected kernel packages.
  • Restrict mounting of untrusted Btrfs filesystem images.
  • Limit mount privileges to trusted administrators and controlled workflows.
  • Review NetApp, Ubuntu, and Debian guidance for environment-specific remediation.

Validation and detection

  • Inventory Linux systems and appliances using or allowing Btrfs mounts.
  • Confirm installed kernel packages include vendor fixes for CVE-2019-19813.
  • Review whether users or automation can mount untrusted filesystem images.
  • Check security advisories from each relevant OS or appliance vendor.
  • Avoid production validation using crafted filesystem images or public proof-of-concept material.
Prepared
Confidence
medium
Sources
7

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.

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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/an/an/aListed
Weakness

CWE details

No CWE listed

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