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

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.

Published: 2025-11-18 Last update: 2026-04-15 Assigner: [email protected] Source: [email protected]
NVD Status：Deferred，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-61661 is rated Low Risk (21.5/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.17%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-61661

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.02% 0.17% +0.15%
2 2025-11-19 — 0.02% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-61661

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.8 3.1 MEDIUM
CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H Click to expand
Attack vector (AV:P)
Hands-on access—USB, keyboard, opening the case—not something you do purely over the wire.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 0.5 4.2 [email protected]

Weakness enumeration for CVE-2025-61661

OS Trackers for CVE-2025-61661

vendor priority summary link
debian not yet assigned CVE-2025-61661 not yet assigned priority: Debian including 1 source packages (grub2), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): open 3, resolved 2. https://security-tracker.debian.org/tracker/CVE-2025-61661
redhat medium — https://access.redhat.com/security/cve/CVE-2025-61661
suse medium — https://www.suse.com/security/cve/CVE-2025-61661/
ubuntu medium CVE-2025-61661 medium priority: Ubuntu including 3 source packages (grub2, grub2-signed, grub2-unsigned), 26 status rows across 9 suites (bionic, focal, jammy, noble, plucky, questing, trusty, upstream, xenial): needs-triage 15, not-affected 7, ignored 4. https://ubuntu.com/security/CVE-2025-61661

Affected software / configurations for CVE-2025-61661

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2025-61661

cvelogic Threat Intelligence