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FedoraOperating system · Fedoraproject

CVE-2022-4283

HIGH · 7.8 CVSS v3.1 Published 2022-12-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
Remediation priority · High
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
A vulnerability was found in X.Org. This security flaw occurs because the XkbCopyNames function left a dangling pointer to freed memory, resulting in out-of-bounds memory access on subsequent XkbGetKbdByName requests.. This issue can lead to local privileges elevation on systems where the X server is running privileged and remote code execution for ssh X forwarding sessions.

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 use-after-free vulnerability in X.Org's XkbCopyNames function leaves a dangling pointer to freed memory, causing out-of-bounds memory access on subsequent XkbGetKbdByName requests. This can be exploited for local privilege escalation on systems with privileged X servers or remote code execution via SSH X forwarding.

MitigationApply available X.Org security patches or upgrade to a patched X server version. As a defense-in-depth measure, disable X11 forwarding in sshd_config or restrict it to trusted hosts until the patch is applied.

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
FedoraOperating system
Affected:= 36= 37
Enterprise LinuxOperating system
Affected:= 6.0= 7.0= 8.0= 9.0
Debian LinuxOperating system
Affected:= 11.0
X ServerApplication
Affected:= 1.20.4

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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. Check installed X.org X Server version
    Run `rpm -qa | grep xorg-x11-server` (RHEL/Fedora) or `dpkg -l | grep xserver-xorg` (Debian) to list installed X server packages and their versions
    Affected if The installed version matches 1.20.4 or falls within the affected ranges (RHEL 6.0-9.0, Fedora 36-37, Debian 11.0)
  2. Verify X server is running
    Run `ps aux | grep Xorg` or `ps aux | grep X` to check if an X server process is active
    Affected if An X server is running and the version is vulnerable per step 1
  3. Check if X keyboard extension (XKB) is in use
    Inspect X server configuration: look for XKB settings in /etc/X11/xorg.conf, /etc/X11/xorg.conf.d/, or check for XKB-related files in /usr/share/X11/xkb/. Alternatively, run `setxkbmap -print` or examine X logs for XKB initialization
    Affected if XKB is enabled and active, since the vulnerability resides in the XkbCopyNames function
  4. Inspect SSH X11 forwarding configuration
    Check /etc/ssh/sshd_config for 'X11Forwarding' directive. Run `grep -i x11forwarding /etc/ssh/sshd_config`
    Affected if X11Forwarding is set to yes (especially on multi-user systems where unprivileged users could exploit the flaw via SSH)
  5. Review X server logs for XkbGetKbdByName usage
    Examine /var/log/Xorg.0.log or current X logs for entries containing 'XkbGetKbdByName' or 'XkbCopyNames'
    Affected if These functions appear in logs, indicating the vulnerable code path is being exercised

A system is affected if it runs a vulnerable X.org X Server version (1.20.4 or affected RHEL/Debian/Fedora versions) with XKB enabled, particularly when X11 forwarding is permitted in SSH.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply available X.Org security patches or upgrade to a patched X server version. As a defense-in-depth measure, disable X11 forwarding in sshd_config or restrict it to trusted hosts until the patch is applied.

Recommended fix Moderate confidence

X.Org Server version newer than 1.20.4 (fixed in subsequent point releases of the xorg-x11-server package)

  1. 1. Identify the operating system and version running on the affected system from: Fedora 36/37, Enterprise Linux 6.0-9.0, Debian 11.0, or X Server 1.20.4
  2. 2. For Fedora systems: Run 'dnf update xorg-x11-server' to apply the latest security update
  3. 3. For Enterprise Linux systems: Run 'yum update xorg-x11-server' or 'dnf update xorg-x11-server' to apply RHSA/ALSA security patches
  4. 4. For Debian systems: Run 'apt-get update && apt-get upgrade xserver-xorg-core' to apply DSA security updates
  5. 5. After updating, restart the X server (or reboot the system) to load the corrected version
  6. 6. Verify the fix by checking the installed version matches a version released after the CVE publication date (December 2022)
Caveat Minor: Some legacy X11 keyboard configuration tools may have minor behavior changes; ensure X configuration files are backed up before updates

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

Fix this in Fedora Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
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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-2022-4283 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