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

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-04-01 · updated 2026-06-17
• Weakness: CWE-401

Description

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.

Affected products

• Linux kernel: from 6.0 before 6.1.132; from 6.2 before 6.6.84; from 6.7 before 6.12.20; from 6.13 before 6.13.8; 6.14-rc1, 6.14-rc2, 6.14-rc3, 6.14-rc4, 6.14-rc5, 6.14-rc6 — fixed in 6.1.132, 6.12.20, 6.13.8, 6.6.84

How to fix

Upgrade to a fixed version: Linux kernel 6.1.132, 6.12.20, 6.13.8, 6.6.84. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/158242b56bf465a73e1edeac0fe828a8acad4499
• https://git.kernel.org/stable/c/24f1bbfb2be77dad82489c1468bbb14312aab129
• https://git.kernel.org/stable/c/ad27b4a51495490b815580d9b935e8eee14d1a9c
• https://git.kernel.org/stable/c/aed709355fd05ef747e1af24a1d5d78cd7feb81e
• https://git.kernel.org/stable/c/c40cd24bfb9bfbb315c118ca14ebe6cf52e2dd1e
• https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html

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