# CVE-2025-61661: Grub2: grub2: out-of-bounds write via malicious usb device

Status: published. Published: 2025-11-18. Updated: 2026-11-05.

A vulnerability has been identified in the GRUB (Grand Unified Bootloader) component. This flaw occurs because the bootloader mishandles string conversion when reading information from a USB device, allowing an attacker to exploit inconsistent length values. A local attacker can connect a maliciously configured USB device during the boot sequence to trigger this issue. A successful exploitation may lead GRUB to crash, leading to a Denial of Service. Data corruption may be also possible, although given the complexity of the exploit the impact is most likely limited.

## Remediation

- workaround: As a mitigation Red Hat doesn't recommend to connect untrusted or unknown USB devices to the machine. (source: CNA: redhat)

## Affected products and versions

- GNU / grub2 (grub2): ≥ 0; ≤ 2.14 (affected, semver). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10 (grub2): Version range not reported. 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 Enterprise Linux 9 (grub2): Version range not reported. Source: CNA: redhat
- Red Hat / Red Hat OpenShift Container Platform 4 (openshift/ose-rhel-coreos-8): 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: 4.8 (medium); CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H; source: CNA: redhat

- CVSS 3.1: 4.8 (medium); CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H; source: NVD: secalert@redhat.com

- CISA KEV: No listing in collected sources

- EPSS: 0.21% as of 2026-11-05; percentile 10.99%

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

- Weaknesses: CWE-131

## Exploit evidence

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

## References

- https://access.redhat.com/security/cve/CVE-2025-61661 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugzilla.redhat.com/show_bug.cgi?id=2413827 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- http://www.openwall.com/lists/oss-security/2025/11/18/8 (ADP: CVE)

- https://access.redhat.com/security/cve/CVE-2025-61661 (secalert@redhat.com)

- https://bugzilla.redhat.com/show_bug.cgi?id=2413827 (secalert@redhat.com)

- http://www.openwall.com/lists/oss-security/2025/11/18/8 (af854a3a-2127-422b-91ae-364da2661108)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2025-61661; retrieved 2026-11-05; source updated 2026-11-05

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-61661; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2025-61661; retrieved 2026-11-05; source updated Not reported

Revision: 2b4c3654c780b2db54404903754524918a2a1227e70c09df09ba978f8acd2175

Canonical: https://y2.dev/cve/CVE-2025-61661

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