PT-2025-14358 · Linux+4 · Linux Kernel+4
Published
2025-02-18
·
Updated
2026-04-20
·
CVE-2025-21977
CVSS v3.1
5.5
Medium
| Vector | AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
Name of the Vulnerable Software and Affected Versions
Linux kernel (affected versions not specified)
Description
A hang issue in the kdump kernel has been resolved when running on Hyper-V Gen 2 VMs. The problem occurs when the hyperv fb driver moves the framebuffer to a different MMIO address due to conflicts with an already-running efifb or simplefb driver. This causes the kdump kernel to access a non-existent framebuffer address, leading to a hang. The issue was originally reported in 2020 and resolved, but a later commit reintroduced the problem. The fix involves reordering the steps in hyperv fb to remove conflicting framebuffers before allocating an MMIO address.
Recommendations
To resolve the issue, update the Linux kernel to a version that includes the fix. As a temporary workaround, consider disabling the hyperv fb driver until a patch is available. Restrict access to the kdump kernel to minimize the risk of exploitation. Avoid using the kexec file load() system call to load the kdump kernel into crash memory, as this can cause the problem to occur. Instead, use the kexec load() system call, which builds the screen info table itself in user space from data returned by the FBIOGET FSCREENINFO ioctl against /dev/fb0.
Exploit
Fix
Improper Resource Release
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Weakness Enumeration
Related Identifiers
Affected Products
Astra Linux
Linuxmint
Linux Kernel
Red Os
Ubuntu