CVE-2024-56738

Information disclosure via early-exit cryptographic comparison

Published Dec 29, 2024 · Updated Dec 31, 2024

Observable timing discrepancy in GNU GRUB 2.00 through 2.12 allows local users to infer compared data via execution timing. The grub_crypto_memcmp routine returns as soon as it finds a differing byte, making execution time depend on the matching prefix of untrusted comparison data. Access to the GRUB console is required, and the reported consequence is information disclosure without data modification or service interruption.

CVSS severity5.3
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Observable timing discrepancy in GNU GRUB 2.00 through 2.12 allows local users to infer compared data via execution timing. The grub_crypto_memcmp routine returns as soon as it finds a differing byte, making execution time depend on the matching prefix of untrusted comparison data. Access to the GRUB console is required, and the reported consequence is information disclosure without data modification or service interruption.

The record

CVE
CVE-2024-56738
Published
Dec 29, 2024
Updated
Dec 31, 2024
Vendor
The GnuPG Project
Product
GNU GRUB
Classifications
CWE-203, CWE-208
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Dec 29, 2024CVE publishedPublication date reported by the CVE source.
  2. Dec 31, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=2.00 <=2.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesadmin

What is affected?

The GnuPG Project · GNU GRUBversion=2.00 <=2.12

Published CVSS scores

4.7SUSECVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
2.3Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
5.7SUSECVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
5.3CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

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)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-203Observable Discrepancy
CWE-208Observable Timing Discrepancy

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo