CVE-2025-54771: GNU GRUB use-after-free in grub_file_close

CVE-2025-54771 · Severity: medium · CVSS 4.9 · Published 2025-11-18

A vulnerability has been found in the GNU GRUB bootloader, the software responsible for starting a computer's operating system. The flaw occurs when the system closes files, potentially allowing the software to crash or behave unpredictably. This could lead to a denial of service or, in some cases, allow an attacker to compromise the integrity of the boot process.

Technologies: Gnu Grub2. Vendors: Gnu.

Quick answers

Is CVE-2025-54771 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2025-54771 being exploited in the wild.
How severe is CVE-2025-54771?
Medium severity, with a CVSS score of 4.9, published 18 November 2025.
Which products and versions are affected?
GNU GRUB2.
Is there a fix for CVE-2025-54771?
A patch was published on 2025-11-18: Security patches released upstream Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2025-54771 attacked?
It is attacked with local access, in an operating system.
Am I affected by CVE-2025-54771?
Check whether you run Gnu Grub2. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

A use-after-free vulnerability exists in the grub_file_close() function of GNU GRUB. The root cause is a failure to properly manage filesystem reference counts; specifically, the code may attempt to access the filesystem structure after its associated module has been dereferenced via grub_dl_unref(). An attacker with local access could exploit this flaw to trigger a crash (Denial of Service) or potentially achieve more complex memory corruption. The vulnerability is addressed by reordering the closing sequence to ensure grub_dl_unref() is called only after the filesystem-specific close operation is complete. Patches have been released by the GRUB maintainers and are being integrated by Linux distributions.

Affected products

  • GNU GRUB2

Timeline

  • 2025-11-10: other: Reported to Red Hat Bugzilla
  • 2025-11-18: disclosed: Public disclosure via oss-security and GNU mailing lists
  • 2025-11-18: patched: Security patches released upstream

References

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