Adobe Acrobat and Reader Prototype Pollution Vulnerability

What it is

Adobe Acrobat and Reader contain a prototype pollution vulnerability that allows for arbitrary code execution.

VulnCheck tracked exploitation 6 days before CISA's KEV listing. VulnCheck's broader catalog of in-the-wild exploitation evidence picked this up before it landed on CISA's formal list. Per-CVE fact about this entry; not a population claim about lead time in general.

Who's affected

Affects anyone opening, editing, or signing PDFs in Adobe Acrobat or Reader. For a CPA or legal practice, PDFs are typically client tax returns, engagement letters, signed agreements, and discovery documents — opening a malicious PDF runs attacker code in the user's session, which can pivot to file shares or email.

What to do

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

If you don't have someone in-house to verify the patch deployed across every endpoint — or you're not sure whether you're affected — that's exactly the kind of triage we do. Book a free 20-minute triage call.

CISA due date

Federal deadline: April 27, 2026. Federal agencies must complete the required action by this date. For private SMBs the deadline is advisory — but treat it as a strong recommendation, especially if you handle regulated data (HIPAA, GLBA, ABA model rules).

EPSS

EPSS score: 7.1% — higher than 94% of all scored CVEs.

EPSS estimates the probability of exploitation activity in the next 30 days. Every entry on this site is already confirmed exploited, so read it as relative urgency among the things you still have open, not as permission to wait.

Score dated 2026-08-12, from the FIRST.org Exploit Prediction Scoring System.

Other exploited Adobe Acrobat and Reader entries

More CISA KEV entries for Adobe Acrobat and Reader. Same product line, same actively-exploited status.

• CVE-2009-3459: Adobe Acrobat and Reader Heap-Based Buffer Overflow Vulnerability
• CVE-2023-21608: Adobe Acrobat and Reader Use-After-Free Vulnerability
• CVE-2023-26369: Adobe Acrobat and Reader Out-of-Bounds Write Vulnerability
• CVE-2018-4990: Adobe Acrobat and Reader Double Free Vulnerability
• CVE-2008-0655: Adobe Acrobat and Reader Unspecified Vulnerability
• CVE-2007-5659: Adobe Acrobat and Reader Buffer Overflow Vulnerability
• CVE-2009-4324: Adobe Acrobat and Reader Use-After-Free Vulnerability
• CVE-2009-3953: Adobe Acrobat and Reader Universal 3D Remote Code Execution Vulnerability

Browse more

• All Adobe KEV entries
• PDF tools
• All SMB-relevant KEV entries

Source

This entry comes from CISA's Known Exploited Vulnerabilities catalog, public US-Government data we pull daily. The plain-language framing and the what-to-do guidance above are ours. View the original entry on cisa.gov.