dbcve.org
Enterprise LinuxOperating system · Redhat

CVE-2022-3775

HIGH · 7.1 CVSS v3.1 Published 2022-12-19
Fix available
A fix is available. Upgrade to after 2.06 or later.
See remediation →
73/100
Remediation priority · Elevated
Zero-click

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 · unedited
When rendering certain unicode sequences, grub2's font code doesn't proper validate if the informed glyph's width and height is constrained within bitmap size. As consequence an attacker can craft an input which will lead to a out-of-bounds write into grub2's heap, leading to memory corruption and availability issues. Although complex, arbitrary code execution could not be discarded.

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 confidence

A heap-based buffer overflow exists in GRUB2's font rendering code when processing certain unicode sequences. The glyph width and height are not properly validated against the bitmap size, allowing an attacker to craft malicious unicode input that triggers an out-of-bounds write into GRUB2's heap memory, leading to memory corruption, denial of service, and potential arbitrary code execution.

MitigationUpdate GRUB2 to the latest patched version that addresses the bounds checking vulnerability in font rendering. Validate and restrict any untrusted font files loaded by the bootloader.

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
Enterprise LinuxOperating system
Affected:= 8.0
Grub2Application
Affected:<= 2.06

CVSS 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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify GRUB2 package version
    On RHEL/CentOS systems, run: rpm -q grub2-common or grub2-pc. On Debian/Ubuntu, run: dpkg -l | grep grub2. On Fedora, run: rpm -q grub2. Check if the version number is 2.06 or lower, or if the package is from RHEL 8.0.
    Affected if The installed GRUB2 version is 2.06 or lower, or the grub2 package version matches RHEL 8.0
  2. Inspect GRUB configuration for font loading directives
    Examine /boot/grub2/grub.cfg or /boot/efi/EFI/*/grub.cfg (path varies by distribution). Look for 'loadfont' commands that specify custom font files. Also check /etc/default/grub for GRUB_FONT settings.
    Affected if Custom font files are loaded via loadfont directive or GRUB_FONT configuration pointing to non-default font files
  3. Check for custom font files in GRUB directories
    List contents of /boot/grub2/fonts/ or /boot/efi/EFI/*/fonts/. Look for any .pf2 font files that are not part of the default OS installation.
    Affected if Non-default or custom .pf2 font files exist in GRUB font directories
  4. Verify GRUB unicode/utf-8 text rendering usage
    Check if GRUB is configured to display text in unicode or if boot menu uses internationalized text. Look for LANG, LC_ALL, or lang settings in /etc/default/grub that enable unicode support.
    Affected if GRUB is configured with internationalization (i18n) settings or unicode text rendering is enabled

A system is likely affected if it runs GRUB2 version 2.06 or earlier (or RHEL 8.0) AND loads custom font files or uses unicode/internationalized text in the boot loader configuration.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to a release after 2.06
Interim mitigation

Update GRUB2 to the latest patched version that addresses the bounds checking vulnerability in font rendering. Validate and restrict any untrusted font files loaded by the bootloader.

Recommended fix Moderate confidence

Grub2 version containing the font rendering vulnerability fix (exact version varies by distribution - consult vendor advisory)

  1. Obtain the latest security advisory for your distribution (Red Hat or Gentoo) to determine the exact fixed Grub2 package version
  2. Update the system package repository metadata
  3. Install the updated grub2 or grub2-common packages using the distribution's package manager (e.g., yum update grub2 or emerge --ask sys-boot/grub)
  4. Rebuild the grub configuration if necessary using grub2-mkconfig
  5. Reboot the system to load the updated GRUB bootloader
Caveat Kernel arguments or custom GRUB modules may need reconfiguration if the update modifies default behaviors; ensure backups of GRUB configurations exist before updating

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Enterprise Linux Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2022-3775 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data