CVE-2021-39839: 
Adobe Acrobat Reader Continuous vulnerability analysis and mitigation

A use-after-free vulnerability was discovered in Adobe Acrobat Reader DC, identified as CVE-2021-39839. The vulnerability was reported on August 4, 2021, and publicly disclosed on September 16, 2021. The flaw specifically exists within the handling of AcroForm fields in Adobe Acrobat Reader DC (ZDI Advisory).

The vulnerability stems from the lack of validation when checking the existence of an object prior to performing operations on it, specifically in the AcroForm getItemAt functionality. The vulnerability has been assigned a CVSS score of 7.8 (AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), indicating its critical severity level (ZDI Advisory).

If successfully exploited, this vulnerability allows remote attackers to execute arbitrary code on affected installations of Adobe Acrobat Reader DC. The execution would occur in the context of the current process, potentially leading to complete system compromise (ZDI Advisory).

Adobe has released security updates to address this vulnerability. Users are advised to apply the security update detailed in Adobe Security Bulletin APSB21-55 (Adobe Security Bulletin).