Remote code execution in Microsoft Excel
| Risk | High |
| Patch available | YES |
| Number of vulnerabilities | 1 |
| CVE-ID | CVE-2021-31939 |
| CWE-ID | CWE-416 |
| Exploitation vector | Network |
| Public exploit | Public exploit code for vulnerability #1 is available. |
| Vulnerable software Subscribe |
Office Online Server Server applications / Other server solutions Microsoft Office Client/Desktop applications / Office applications Microsoft Excel Client/Desktop applications / Office applications Microsoft Office Web Apps Server Server applications / Application servers |
| Vendor | Microsoft |
Security Bulletin
This security bulletin contains one high risk vulnerability.
1) Use-after-free
EUVDB-ID: #VU53912
Risk: High
CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]
CVE-ID: CVE-2021-31939
CWE-ID:
CWE-416 - Use After Free
Exploit availability: Yes
DescriptionThe vulnerability allows a remote attacker to compromise vulnerable system.
The vulnerability exists due to a use-after-free error when processing Excel files. A remote attacker can create a specially crafted Excel file, trick the victim into opening it, trigger a use-after-free error and execute arbitrary code on the system.
Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.
MitigationInstall updates from vendor's website.
Vulnerable software versionsOffice Online Server : 2016
Microsoft Office: 2013 - 2019
Microsoft Excel: 2013 - 2016
Microsoft Office Web Apps Server: 2013 Service Pack 1
External linkshttp://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31939
http://www.zerodayinitiative.com/advisories/ZDI-21-670/
Q & A
Can this vulnerability be exploited remotely?
Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.
Is there known malware, which exploits this vulnerability?
No. We are not aware of malware exploiting this vulnerability.
