Exploited vulnerability · CISA KEV

Is CVE-2026-34621 exploited? Yes: in CISA KEV since 13 Apr 2026

Gociux · Adobe Acrobat and Reader · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2026-34621, Adobe Acrobat and Reader Prototype Pollution Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 13 Apr 2026, 2 days after it was published. It affects Adobe Acrobat and Reader. If you run it, CISA's required action is: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

What it is

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

What to do

1. Check whether you run it. Look for Acrobat and Reader in your asset inventory, including appliances and cloud images. Stack check lists every exploited Adobe CVE at once.
2. Apply the fix. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 11 Apr 2026.
4. Get told next time. Email alerts when CISA adds a CVE for Adobe.

Other exploited CVEs in Acrobat and Reader

• CVE-2009-3459: Adobe Acrobat and Reader Heap-Based Buffer Overflow Vulnerability (20 May 2026)
• CVE-2023-21608: Adobe Acrobat and Reader Use-After-Free Vulnerability (10 Oct 2023)
• CVE-2023-26369: Adobe Acrobat and Reader Out-of-Bounds Write Vulnerability (14 Sep 2023)
• CVE-2018-4990: Adobe Acrobat and Reader Double Free Vulnerability (8 Jun 2022)
• CVE-2010-2883: Adobe Acrobat and Reader Stack-Based Buffer Overflow Vulnerability (8 Jun 2022)
• CVE-2009-4324: Adobe Acrobat and Reader Use-After-Free Vulnerability (8 Jun 2022)

References

• helpx.adobe.com/security/products/acrobat/apsb26-43.html
• nvd.nist.gov/vuln/detail/CVE-2026-34621

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in April 2026 · Adobe scorecard · act-now radar.