CVE-2026-34621: Adobe Acrobat and Reader Prototype Pollution Vulnerability

Vulnerability summary

CVE-2026-34621 is a high (CVSS 8.6) vulnerability in Adobe Acrobat and Reader. It is known to be exploited: CISA lists it, first on 13-04-2026. EPSS estimates a 7.23% chance of exploitation in the next 30 days, higher than 94.3% of scored vulnerabilities.

Timeline

1. 11-04-2026
   PublishedVulnerability first disclosed.
2. 13-04-2026
   Added to CISA KEVExploitedAdobe Acrobat and Reader Prototype Pollution Vulnerability
3. 27-04-2026
   CISA remediation dueDeadline passedApply mitigations per vendor instructions.
4. 27-08-2026
   Last modifiedVulnerability information updated.

Description

Acrobat Reader versions 24.001.30356, 26.001.21367 and earlier are affected by an Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') vulnerability that could result in 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.

• CWE-1321Improperly Controlled Modification of Object Prototype AttributesThe product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.