What is CVE-2026-34621?

CVE-2026-34621 is a high-severity vulnerability in Adobe Acrobat Reader, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 8.6/10. Published 2026-04-11.

How severe is CVE-2026-34621?

High severity. CVSS v3 base score is 8.6 out of 10.

Is CVE-2026-34621 known to be exploited?

Yes. CVE-2026-34621 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-04-13), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.

Prototype Pollution in Adobe Acrobat Reader

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…

Vulnerability class: Prototype Pollution

EPSS: 0.098 (93.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.6 (High). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H.

Affected products

Adobe Acrobat Reader — versions 0

Weakness classification (CWE)

CWE-1321 — Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution)

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2026-04-13. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2026-04-27.

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

Public proof-of-concept exploits

References

helpx.adobe.com/security/products/acrobat/apsb26-43.html (vendor-advisory)

Frequently asked questions

What is CVE-2026-34621?: CVE-2026-34621 is a high-severity vulnerability in Adobe Acrobat Reader, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 8.6/10. Published 2026-04-11.
How severe is CVE-2026-34621?: High severity. CVSS v3 base score is 8.6 out of 10.
Is CVE-2026-34621 known to be exploited?: Yes. CVE-2026-34621 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2026-04-13), indicating it is being actively exploited. 5 public proof-of-concept repositories are indexed.