CVE-2025-21978

Denial of service via MMIO mapping leak

Published Apr 1, 2025 · Updated May 11, 2026

Resource leak in the Hyper-V DRM driver in Linux allows local users to exhaust kernel virtual address space during device teardown. The removal and probe-error paths release VRAM MMIO space without calling iounmap(), leaving each cacheable mapping allocated. The flaw requires local low-privileged access and an affected Hyper-V DRM device; accumulated mappings can deny kernel memory resources.

CVSS severity5.5
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource leak in the Hyper-V DRM driver in Linux allows local users to exhaust kernel virtual address space during device teardown. The removal and probe-error paths release VRAM MMIO space without calling iounmap(), leaving each cacheable mapping allocated. The flaw requires local low-privileged access and an affected Hyper-V DRM device; accumulated mappings can deny kernel memory resources.

The record

CVE
CVE-2025-21978
Published
Apr 1, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 1, 2025CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.0
  2. Affected versionversion=a0ab5abced550ddeefddb06055ed60779a54eb79 <158242b56bf465a73e1edeac0fe828a8acad4499
  3. Affected versionversion=a0ab5abced550ddeefddb06055ed60779a54eb79 <24f1bbfb2be77dad82489c1468bbb14312aab129
  4. Affected versionversion=a0ab5abced550ddeefddb06055ed60779a54eb79 <ad27b4a51495490b815580d9b935e8eee14d1a9c
  5. Affected versionversion=a0ab5abced550ddeefddb06055ed60779a54eb79 <aed709355fd05ef747e1af24a1d5d78cd7feb81e
  6. Affected versionversion=a0ab5abced550ddeefddb06055ed60779a54eb79 <c40cd24bfb9bfbb315c118ca14ebe6cf52e2dd1e

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=6.0; version=a0ab5abced550ddeefddb06055ed60779a54eb79 <158242b56bf465a73e1edeac0fe828a8acad4499; version=a0ab5abced550ddeefddb06055ed60779a54eb79 <24f1bbfb2be77dad82489c1468bbb14312aab129; version=a0ab5abced550ddeefddb06055ed60779a54eb79 <ad27b4a51495490b815580d9b935e8eee14d1a9c; version=a0ab5abced550ddeefddb06055ed60779a54eb79 <aed709355fd05ef747e1af24a1d5d78cd7feb81e; version=a0ab5abced550ddeefddb06055ed60779a54eb79 <c40cd24bfb9bfbb315c118ca14ebe6cf52e2dd1e

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
6.8SUSECVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
5.5SUSECVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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