CVE-2024-31081 – A heap-based buffer over-read vulnerability in ... (How to Fix)

Q: What is the severity of CVE-2024-31081?

CVE-2024-31081 has a CVSS score of 7.3 (HIGH). A heap-based buffer over-read vulnerability in the X.org server's ProcXIPassiveGrabDevice() function allows attackers to cause memory leaks and segmentation faults. This occurs when byte-swapped length values are used in replies, potentially leading to crashes when triggered by clients with different endianness. Systems running vulnerable X.org server versions are affected.

📋 TL;DR

A heap-based buffer over-read vulnerability in the X.org server's ProcXIPassiveGrabDevice() function allows attackers to cause memory leaks and segmentation faults. This occurs when byte-swapped length values are used in replies, potentially leading to crashes when triggered by clients with different endianness. Systems running vulnerable X.org server versions are affected.

💻 Affected Systems

Products:

X.org X Server

Versions: Versions prior to fixes in Red Hat advisories RHSA-2024:1785, RHSA-2024:2036-2039

Operating Systems: Linux distributions using X.org server (RHEL, Fedora, CentOS, etc.)

Default Config Vulnerable: ⚠️ Yes

Notes: Only affects systems using X.org server with X Input Extension (XInput) enabled, which is common in graphical Linux environments.

⚠️ Manual Verification Required

This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.

Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).

🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.

Recommended Actions:

Review the CVE details at NVD
Check vendor security advisories for your specific version
Test if the vulnerability is exploitable in your environment
Consider updating to the latest version as a precaution

⚠️ Risk & Real-World Impact

🔴

Worst Case

Denial of service through X server crash, potentially disrupting graphical sessions and applications relying on X11.

🟠

Likely Case

Service disruption through X server crashes, requiring restart of graphical sessions.

🟢

If Mitigated

Limited impact with proper network segmentation and access controls preventing untrusted clients from connecting.

🌐 Internet-Facing: LOW - X servers are typically not directly internet-facing, but could be exposed via remote X11 forwarding.

🏢 Internal Only: MEDIUM - Internal attackers or compromised systems could exploit this to disrupt graphical sessions.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires sending specially crafted X11 protocol messages to trigger the buffer over-read condition.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Versions containing fixes from Red Hat advisories

Vendor Advisory: https://access.redhat.com/errata/RHSA-2024:1785

Restart Required: Yes

Instructions:

1. Update X.org server packages using your distribution's package manager. 2. For RHEL/CentOS: 'yum update xorg-x11-server*'. 3. Restart the X server or reboot the system.

🔧 Temporary Workarounds

Disable X Input Extension

linux

Disable X Input Extension (XInput) if not required, though this may break functionality for some input devices.

Not recommended as it breaks functionality; better to patch

Network Access Controls

linux

Restrict X server access to trusted clients only using xhost or X11 forwarding restrictions.

xhost -
xhost +local:

🧯 If You Can't Patch

Implement strict network segmentation to prevent untrusted clients from connecting to X servers
Monitor for X server crashes and implement restart automation for critical systems

🔍 How to Verify

Check if Vulnerable:

Check X.org server version: 'Xorg -version' and compare against patched versions in Red Hat advisories.

Check Version:

Xorg -version 2>&1 | grep -i 'x.org x server'

Verify Fix Applied:

Verify updated package version: 'rpm -q xorg-x11-server-Xorg' (RHEL/CentOS) or equivalent for your distribution.

📡 Detection & Monitoring

Log Indicators:

X server segmentation fault messages in system logs
X server crash reports in /var/log/Xorg.*.log

Network Indicators:

Unusual X11 protocol traffic patterns
Multiple connection attempts to X server port 6000+

SIEM Query:

source="Xorg" AND ("segmentation fault" OR "crash" OR "SIGSEGV")

📊 Metadata

CVE ID: CVE-2024-31081

CVSS v3 Score: 7.3 (HIGH)

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

CWE: CWE-126

Published: April 4, 2024

Last Updated: August 4, 2025

🔗 References

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