# CVE-2025-0677: Grub2: ufs: integer overflow may lead to heap based out-of-bounds write when handling symlinks

Status: published. Published: 2025-02-19. Updated: 2026-11-05.

A flaw was found in grub2. When performing a symlink lookup, the grub's UFS module checks the inode's data size to allocate the internal buffer to read the file content, however, it fails to check if the symlink data size has overflown. When this occurs, grub_malloc() may be called with a smaller value than needed. When further reading the data from the disk into the buffer, the grub_ufs_lookup_symlink() function will write past the end of the allocated size. An attack can leverage this by crafting a malicious filesystem, and as a result, it will corrupt data stored in the heap, allowing for arbitrary code execution used to by-pass secure boot mechanisms.

## Remediation

- workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. (source: CNA: redhat)

## Affected products and versions

-  /  (grub2): ≥ 0; ≤ 2.12 (affected, semver). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (grub2): ≥ 1:2.12-15.el10_0; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (grub2): ≥ 1:2.06-104.el9_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 7 (grub2): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (grub2): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-9): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 6.4 (medium); CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.33% as of 2026-11-05; percentile 26.07%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-787

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2025:16154 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2025:6990 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2025-0677 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2346116 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://lists.gnu.org/archive/html/grub-devel/2025-02/msg00024.html (CNA: redhat)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2025-0677; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2025-0677; retrieved 2026-11-05; source updated Not reported

Revision: 9beffdd7eb85d3a51d4493391f9f49e9bdfca3c270586312fc9e1da098f74c8d

Canonical: https://y2.dev/cve/CVE-2025-0677

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