CVE-2026-34621 is a prototype pollution vulnerability in Adobe Acrobat Reader that affects versions 24.001.30356, 26.001.21367 and earlier. This vulnerability allows improper modification of object prototype attributes, which can lead to arbitrary code execution in the context of the current user. Exploitation requires that a victim opens a malicious file. The vulnerability has a CVSS v3.1 base score of 9.6, reflecting network attack vector, low attack complexity, no privileges required, user interaction required, scope change, and high impact on confidentiality, integrity, and availability. No patch or official remediation level is currently documented.

Successful exploitation can lead to arbitrary code execution with the privileges of the current user, potentially compromising confidentiality, integrity, and availability of the affected system. Because user interaction is required, the attack vector involves tricking a user into opening a malicious file. There are no known exploits in the wild, which may reduce immediate risk but does not eliminate the threat.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is available, users should exercise caution when opening files from untrusted sources. Monitor Adobe's security advisories for updates regarding patches or mitigations.