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CVE-2026-34621

Adobe Acrobat And Reader•HIGH · CVSS 8.6• In the wild In CISA KEV

What is CVE-2026-34621?

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.

CVSS8.6 NVD 3.1

SeverityHIGH

Exploitation In the wild In CISA KEV

EPSS2% · P82

Triage statusActive Exploit

ActionPatch immediately

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

CWECWE-1321

NVD published2026-04-11

NVD last modified2026-08-28

Timeline

2026-04-11Published to the U.S. National Vulnerability Database (NVD)
2026-04-13First covered in a defend.network daily briefing
2026-04-13Added to the CISA Known Exploited Vulnerabilities (KEV) catalog
2026-04-27CISA federal remediation deadline (BOD 22-01)
2026-08-28NVD record last updated

CISA Known Exploited Vulnerability

Adobe Acrobat and Reader Prototype Pollution Vulnerability

Added to KEV2026-04-13

Federal patch deadline2026-04-27

Known ransomware useUnknown

Affected product

Adobe Acrobat And Reader

NVD also lists CPE entries for: Adobe Acrobat Dc, Adobe Acrobat Reader Dc, Adobe Acrobat, Apple Macos, Microsoft Windows

Remediation Steps

Deploy Adobe Acrobat Reader emergency patch released April 2026 to all endpoints
Implement application control to block execution of unpatched Reader versions
Disable JavaScript execution in Adobe Reader as temporary mitigation if patching delayed
Monitor for exploitation attempts using EDR/XDR tools with CVE-2026-34621 signatures
Educate users against opening untrusted PDF attachments

References

Referenced in our briefings & reports

Vulnerability Priority Report – Week 2 of April 2026 (April 13 – 19)
Adobe Reader zero-day; CPUID STX RAT supply-chain; Iran hits 4,000 ICS (2026-04-13)

Related vulnerabilities

CVE-2026-75682 – Adobe Connect (same product)
CVE-2026-11645 – Google Chromium V8 (same product)
CVE-2026-5281 – Google Dawn (same product)
CVE-2026-96951 – Microsoft Windows (same product)
CVE-2026-86950 – Apple Multiple Products (same product)
CVE-2026-81963 – Microsoft Windows (same product)

Adobe: 82 known exploited vulnerabilities (CISA KEV) →

Browse all tracked CVEs in the defend.network CVE database →

🤖 This CVE page is generated by defend.network from NVD, CISA KEV, EPSS, and our verified daily briefings. Severity and exploitation data come from official sources; always verify remediation steps against the official vendor advisory before acting in production.