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Fencer Vulns
medium 5.3

CVE-2024-56738 json

GNU GRUB (aka GRUB2) through 2.12 does not use a constant-time algorithm for grub_crypto_memcmp and thus allows side-channel attacks.

published 2024-12-29 22 mo ago modified 2026-06-17 4 mo ago also EUVD-2024-53381

cvss
5.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 34%
public exploits
0
none known

Summary

GNU GRUB (aka GRUB2) through 2.12 does not use a constant-time algorithm for grub_crypto_memcmp and thus allows side-channel attacks.

Patch / fix

  • grub2 SLES 16.0, Linux Micro 6.2, SLES for SAP applications 16.0 2.12-160000.3.1
  • grub2 Linux Micro 6.1 2.12-slfo.1.1_2.1
  • grub2 Linux Micro 6.0 2.12~rc1-7.1
  • grub2 SLE Module for Server Applications 15 SP7, SLE Module for Basesystem 15 SP7 2.12-150700.19.13.2
  • grub2 SLE Module for Server Applications 15 SP6, SLE Module for Basesystem 15 SP6, openSUSE Leap 15.6 2.12-150600.8.34.1
  • grub2 SLE Micro 5.4, SLE Micro 5.3 2.06-150400.11.63.1
  • grub2 SLE Micro 5.1 2.04-150300.3.14.2
  • grub2 SLE Micro 5.5 2.06-150500.29.53.1

suse advisories SUSE-SU-2025:21212-1SUSE-SU-2025:21223-1SUSE-SU-2025:20863-1SUSE-SU-2025:20654-1SUSE-SU-2025:02813-1SUSE-SU-2025:02772-1

  • grub2 openSUSE Leap 16.0 2.12-160000.3.1
  • grub2 openSUSE Tumbleweed 2.12-56.1

opensuse advisories openSUSE-SU-2025:20163-1openSUSE-SU-2025:15400-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2024-56738 updated cvss 6.5

grub2: Observable Timing Discrepancy resulting side-channel attacks

  • Red Hat Enterprise Linux 7 grub2, grub2-pc, grub2-efi, grub2-ppc64, grub2-tools, grub2-common, +15 more Red Hat Enterprise Linux 8 grub2, grub2-pc, grub2-tools, grub2-common, grub2-efi-x64, grub2-ppc64le, +13 more
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 9 grub2, grub2-pc, grub2-tools, grub2-common, grub2-efi-x64, grub2-ppc64le, +10 more Red Hat Enterprise Linux 10 grub2
    affected: no fix planned “Will not fix”
  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-9
    affected: no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
22 mo ago

Exploit prediction

0.40% chance of exploitation in the next 30 days, higher than 34% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected products

  • GNU GRUB2

Classification

Weakness
  • CWE-208 Observable Timing Discrepancy
  • CWE-203 Observable Discrepancy

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.