LiveActive security incident?Get immediate response
CVE Record

CVE-2025-21978: drm/hyperv: Fix address space leak when Hyper-V DRM device is removed

In the Linux kernel, the following vulnerability has been resolved: drm/hyperv: Fix address space leak when Hyper-V DRM device is removed When a Hyper-V DRM device is probed, the driver allocates MMIO space for the vram, and maps it cacheable. If the device removed, or in the error path for device probing, the MMIO space is released but no unmap is done. Consequently the kernel address space for the mapping is leaked. Fix this by adding iounmap() calls in the device removal path, and in the error path during device probing.

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysislow

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue leaks kernel address space when a Hyper-V DRM graphics device is removed or probe setup fails. The source describes a cleanup bug, not a remote takeover. Business risk is mainly stability and reliability for affected virtualized Linux systems until fixed kernels are deployed.

Executive priority

Treat as a routine kernel maintenance item unless Hyper-V Linux workloads are highly availability-sensitive. No source evidence supports emergency response or active exploitation, but fixed kernels should enter normal patch cycles.

Technical view

The Hyper-V DRM driver maps VRAM MMIO space as cacheable during probe. On device removal or probe failure, it released MMIO space without calling iounmap(), leaving the kernel mapping behind. Upstream stable commits add iounmap() cleanup in both paths.

Likely exposure

Exposure is most relevant to Linux systems using the Hyper-V DRM driver, especially where Hyper-V DRM devices can be removed, reprobed, or fail during initialization. The bundle lists Linux kernel versions and stable fix commits but does not provide full distribution-specific version mapping beyond Debian LTS.

Exploitation context

The bundle does not show active exploitation, KEV listing, public exploit details, or CVSS scoring. The described impact is a kernel address space leak from incomplete driver cleanup, which may contribute to resource exhaustion or instability rather than direct compromise.

Researcher notes

The useful validation question is whether the deployed kernel contains the specific DRM Hyper-V cleanup patch or a vendor backport. Source data is limited: severity, CVSS, CWE, and exploitability indicators are not provided.

Mitigation direction

  • Update affected Linux kernels to vendor releases containing the Hyper-V DRM iounmap() fix.
  • Review Linux stable commit references for the exact branches used in your fleet.
  • Follow Debian LTS guidance where Debian kernels are deployed.
  • If fixed packages are unavailable, monitor vendor guidance and plan kernel maintenance promptly.

Validation and detection

  • Inventory Linux kernel versions on systems using Hyper-V DRM functionality.
  • Confirm the running kernel includes the relevant stable fix commit or vendor backport.
  • Check distribution advisories for package-level fixed versions before closing findings.
  • Prioritize validation on virtualized Linux hosts where Hyper-V DRM is enabled.
Prepared
Confidence
medium
Sources
8

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2025-21978 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
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
1ADP providers
7Source links

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

CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxa0ab5abced550ddeefddb06055ed60779a54eb79, a0ab5abced550ddeefddb06055ed60779a54eb79, a0ab5abced550ddeefddb06055ed60779a54eb79, a0ab5abced550ddeefddb06055ed60779a54eb79, a0ab5abced550ddeefddb06055ed60779a54eb79unaffected
LinuxLinux6.0, 0, 6.1.132, 6.6.84, 6.12.20, 6.13.8, 6.14affected
Weakness

CWE details

No CWE listed

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