CVE-2024-56738
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedGNU GRUB (aka GRUB2) through 2.12 does not use a constant-time algorithm for grub_crypto_memcmp and thus allows side-channel attacks.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceGNU GRUB2 through version 2.12 contains a timing side-channel vulnerability in the grub_crypto_memcmp function, which compares cryptographic values using a non-constant-time algorithm. Attackers can exploit timing differences in the comparison to leak information about sensitive data like password hashes or keys.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data<= 2.12CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Determine installed GRUB2 versionRun 'grub-install --version' or check the package manager (dpkg -l grub* or rpm -q grub2) to retrieve the installed version numberAffected if The installed GRUB2 version is 2.12 or lower
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Verify GRUB2 is the active bootloaderCheck the boot configuration - on BIOS systems inspect the Master Boot Record (MBR) or on UEFI systems check /boot/efi/EFI/*/grubx64.efi. Commands like 'efibootmgr -v' (Linux) or 'bcdedit /enum firmware' (Windows) can show the configured bootloaderAffected if GRUB2 is configured as the primary bootloader for the system
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Confirm the vulnerable function exists in the binaryExamine the GRUB2 binary or shared library (typically /usr/lib/grub/x86_64-pc/grub.cfg or the grubx64.efi file) for the presence of the grub_crypto_memcmp function using tools like 'strings' or 'objdump'Affected if The grub_crypto_memcmp function is present in the GRUB2 binary and the version is <= 2.12
The system is affected if GRUB2 version 2.12 or earlier is installed and actively used as the bootloader, with the vulnerable grub_crypto_memcmp function present in the binary.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scopedUpgrade GRUB2 to version 2.12 or later where the constant-time comparison is implemented, or apply vendor-provided patches that replace grub_crypto_memcmp with a constant-time algorithm.
GRUB2 version > 2.12 with constant-time grub_crypto_memcmp implementation
- 1. Identify the current installed GRUB2 version using: rpm -q grub2 or dpkg -l grub-pc
- 2. Check if your distribution has released a version newer than 2.12 that addresses this vulnerability
- 3. If a fixed version is available from your distribution vendor, update using: yum update grub2 (RHEL/CentOS) or apt update && apt install grub2 (Debian/Ubuntu)
- 4. If no vendor update is available, rebuild GRUB2 from source with the constant-time crypto patch applied
- 5. Regenerate GRUB configuration and reinstall GRUB to MBR/EFI after update: grub2-mkconfig -o /boot/grub2/grub.cfg && grub2-install /dev/sda (or your boot device)
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2024-56738 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2024-56738 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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