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CVE-2023-6816VulnerabilityPublished Updated

CVE-2023-6816: Red Hat Enterprise Linux 6 Extended Lifecycle Support – EXTENSION · Out-of-bounds Write

Affects Red Hat Enterprise Linux 6 Extended Lifecycle Support – EXTENSIONSource CVE Database V5

0

Not known to be exploited · CVSS 9.8 Critical.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
2.1% chance of exploitation in 30 days – higher than 81% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 18 Jan 2024

  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 2026-10-26.

What to do

AI-suggested

To mitigate CVE-2023-6816, European organizations should prioritize the following actions: 1) Apply any available patches or updates from Red Hat as soon as they are released; monitor Red Hat advisories closely. 2) If patches are not yet available, consider disabling or restricting access to the X.Org server, especially on systems exposed to untrusted networks. 3) Implement network-level controls such as firewall rules to limit access to ports used by X.Org server input services. 4) Employ intrusion detection and prevention systems to monitor for anomalous input device events or unusual network traffic patterns targeting X.Org. 5) Review and harden system configurations to minimize attack surface, including removing unnecessary input device drivers or services. 6) For legacy systems that cannot be patched promptly, consider isolating them within segmented network zones with strict access controls. 7) Conduct thorough incident response planning and readiness in case exploitation attempts are detected. 8) Engage with Red Hat support for guidance on extended lifecycle vulnerabilities and potential backported fixes. These steps go beyond generic advice by focusing on legacy system constraints and network-based mitigations.

Description

A flaw was found in X.Org server. Both DeviceFocusEvent and the XIQueryPointer reply contain a bit for each logical button currently down. Buttons can be arbitrarily mapped to any value up to 255, but the X.Org Server was only allocating space for the device's particular number of buttons, leading to a heap overflow if a bigger value was used.

References

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