Foxit PDF Reader FoxitUpdater Race Condition Local Privilege Escalation Vulnerability

September 23rd, 2026
ZDI-26-742 ZDI-CAN-32454

CVE ID

CVE-2026-91813

CVSS Score

7.8 AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Vendors

Foxit

Affected Products

PDF Reader

Vulnerability Details

This vulnerability allows local attackers to escalate privileges on affected installations of Foxit PDF Reader. 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 update functionality. The issue results from the lack of proper locking when performing operations on an object. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of SYSTEM.

Additional Details

Foxit has issued an update to correct this vulnerability. More details can be found at:
https://www.foxit.com/support/security-bulletins.html

Disclosure Timeline

  • 2026-08-20 - Vulnerability reported to vendor
  • 2026-09-23 - Coordinated public release of advisory
  • 2026-09-23 - Advisory Updated

Credit

praydog & kmx00

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