CVE-2025-21978: Linux kernel · Memory Leak
Source GCVE Database
Not known to be exploited · CVSS 5.5 Medium.
Data as of 30 Oct 2026, 01:26 UTC
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 Apr 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
AI-suggested
A fix has been implemented that adds iounmap() calls in the device removal and error paths to properly unmap MMIO space. Although no explicit patch links are provided, the vulnerability description confirms the issue is resolved. Users should update their Linux kernel to a version that includes this fix once available.
Description
CVE-2025-21978 is a medium severity vulnerability in the Linux kernel's Hyper-V DRM driver. It involves an address space leak caused by failure to unmap MMIO space when the Hyper-V DRM device is removed or when device probing fails. This leak can lead to resource exhaustion in the kernel address space.
References
- nvd.nist.gov/vuln/detail/CVE-2025-21978 (opens in a new tab)
- git.kernel.org/stable/c/158242b56bf465a73e1edeac0fe828a8acad4499 (opens in a new tab)
- git.kernel.org/stable/c/24f1bbfb2be77dad82489c1468bbb14312aab129 (opens in a new tab)
- git.kernel.org/stable/c/ad27b4a51495490b815580d9b935e8eee14d1a9c (opens in a new tab)
- git.kernel.org/stable/c/aed709355fd05ef747e1af24a1d5d78cd7feb81e (opens in a new tab)
- git.kernel.org/stable/c/c40cd24bfb9bfbb315c118ca14ebe6cf52e2dd1e (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/05/msg00045.html (opens in a new tab)