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VulnerabilityPublished Updated

CVE-2023-5574: Red Hat Enterprise Linux 9 · Use After Free

Affects Red Hat Enterprise Linux 9Source CVE Database V5

0

Not known to be exploited · CVSS 7.0 High.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score
7.0High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 25 Oct 2023

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

AI-suggested

To mitigate CVE-2023-5574, European organizations should first identify any systems running Red Hat Enterprise Linux 9 with Xvfb configured in Zaphod mode. Since this configuration is legacy and uncommon, disabling Zaphod mode or avoiding multi-screen setups with multiple protocol screens is recommended. Organizations should monitor Red Hat advisories closely and apply official patches or updates as soon as they become available. In the interim, restrict local access to trusted users only, as exploitation requires local privileges. Implement strict access controls and auditing on systems running Xvfb to detect any suspicious activity. Consider isolating vulnerable systems or migrating workloads to environments not using Xvfb or legacy multi-screen configurations. Additionally, review shutdown and reset procedures for graphical servers to ensure they do not trigger unsafe pointer operations. Regularly update and harden Linux systems to reduce attack surfaces and maintain secure configurations. Employ endpoint detection and response tools to monitor for anomalous behavior indicative of exploitation attempts.

Description

A use-after-free flaw was found in xorg-x11-server-Xvfb. This issue occurs in Xvfb with a very specific and legacy configuration (a multi-screen setup with multiple protocol screens, also known as Zaphod mode). If the pointer is warped from a screen 1 to a screen 0, a use-after-free issue may be triggered during shutdown or reset of the Xvfb server, allowing for possible escalation of privileges or denial of service.

References

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