Advisory Details

December 9th, 2020

X.Org Server XIChangeHierarchy Integer Underflow Privilege Escalation Vulnerability

ZDI-20-1417
ZDI-CAN-11429

CVE ID CVE-2020-14346
CVSS SCORE 7.8, (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
AFFECTED VENDORS X.Org
AFFECTED PRODUCTS Server
VULNERABILITY DETAILS

This vulnerability allows local attackers to escalate privileges on affected installations of X.Org Server. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the handling of XIChangeHierarchy requests. The issue results from the lack of proper validation of user-supplied data, which can result in an integer underflow before writing to memory. An attacker can leverage this vulnerability to escalate privileges and execute code in the context of root.

ADDITIONAL DETAILS X.Org has issued an update to correct this vulnerability. More details can be found at:
https://lists.x.org/archives/xorg-announce/2020-August/003058.html
DISCLOSURE TIMELINE
  • 2020-07-24 - Vulnerability reported to vendor
  • 2020-12-09 - Coordinated public release of advisory
CREDIT Jan-Niklas Sohn
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