Advisory Details

September 16th, 2021

Microsoft Word DOC File Parsing Use-After-Free Remote Code Execution Vulnerability

ZDI-21-1082
ZDI-CAN-13918

CVE ID CVE-2021-38656
CVSS SCORE 7.8, AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
AFFECTED VENDORS Microsoft
AFFECTED PRODUCTS Word
VULNERABILITY DETAILS

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Microsoft Word. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the parsing of DOC files. Crafted data in a DOC file can cause a pointer to be reused after it has been freed. An attacker can leverage this vulnerability to execute code in the context of the current process.

ADDITIONAL DETAILS Microsoft has issued an update to correct this vulnerability. More details can be found at:
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-38656
DISCLOSURE TIMELINE
  • 2021-07-09 - Vulnerability reported to vendor
  • 2021-09-16 - Coordinated public release of advisory
CREDIT kdot
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