CVE-2021-21017

CVE-2021-21017 is a high-severity (CVSS 8.8) vulnerability in Adobe Acrobat and Reader. CISA added it to the Known Exploited Vulnerabilities catalog on November 3, 2021, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by November 17, 2021. CISA does not currently list it as used in ransomware campaigns. Adobe has 82 vulnerabilities in the KEV catalog, 11 of them linked to ransomware.

Acrobat Reader DC versions versions 2020.013.20074 (and earlier), 2020.001.30018 (and earlier) and 2017.011.30188 (and earlier) are affected by a heap-based buffer overflow vulnerability. An unauthenticated attacker could leverage this vulnerability to achieve arbitrary code execution in the context of the current user. Exploitation of this issue requires user interaction in that a victim must open a malicious file.

CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

• https://helpx.adobe.com/security/products/acrobat/apsb21-09.html
• https://helpx.adobe.com/security/products/acrobat/apsb21-09.html
• https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21017