CVE-2025-61661

Bootloader crash via inconsistent USB string lengths

Published Nov 18, 2025 · Updated Sep 1, 2026

Out-of-bounds write in GNU GRUB 2.14 and earlier allows physically proximate attackers to crash the bootloader via a malicious USB device. grub_usb_get_string() allocates the UTF-8 destination using the first USB descriptor's length but converts a second descriptor using its potentially larger length. Exploitation requires malicious USB hardware during boot and can cause a heap overflow, boot failure, or limited data corruption.

CVSS severity4.8
Medium
EPSS probability0.19%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in GNU GRUB 2.14 and earlier allows physically proximate attackers to crash the bootloader via a malicious USB device. grub_usb_get_string() allocates the UTF-8 destination using the first USB descriptor's length but converts a second descriptor using its potentially larger length. Exploitation requires malicious USB hardware during boot and can cause a heap overflow, boot failure, or limited data corruption.

The record

CVE
CVE-2025-61661
Published
Nov 18, 2025
Updated
Sep 1, 2026
Vendor
The GnuPG Project
Product
GNU GRUB
Classifications
CWE-131, T1200
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Nov 18, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=2.14

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

The GnuPG Project · GNU GRUBversion=0 <=2.14
389 Directory Server · Red Hat Enterprise Linux 10Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 7Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 9Affected versions are unavailable in this record.
389 Directory Server · Red Hat OpenShift Container Platform 4Affected versions are unavailable in this record.
389 Directory Server · Red Hat Enterprise Linux 8Affected versions are unavailable in this record.

Published CVSS scores

4.8Red Hat, Inc.CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-131Incorrect Calculation of Buffer Size
T1200Hardware Additions

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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