How severe is CVE-2026-34621?

CVE-2026-34621 has a CVSS score of 8.6/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-34621?

Affected package information for CVE-2026-34621 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2026-34621?

No fixed version has been published for CVE-2026-34621 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2026-34621 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2026-34621, including . All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2026-34621?

CVE-2026-34621 has an EPSS (Exploit Prediction Scoring System) score of 11.0%, placing it in the 94th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

Is CVE-2026-34621 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2026-34621 (Adobe Acrobat and Reader Prototype Pollution Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-04-13. CISA required all US federal civilian agencies to remediate this vulnerability by 2026-04-27. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2026-34621?

CVE-2026-34621 is classified as CWE-1321 (CWE-1321). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

Which products and versions are affected by CVE-2026-34621?

CVE-2026-34621 affects adobe acrobat; adobe acrobat dc; adobe acrobat reader dc. Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2026-34621 published, and has it been updated?

CVE-2026-34621 was published on April 11, 2026 and was last updated on April 13, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2026-04-13 — agencies required to remediate by 2026-04-27

CVE-2026-34621

HIGH

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…

Published

Apr 11, 2026

Updated

Apr 13, 2026

Affected

0 pkgs

Patched

None yet

Exploits

1 known

EPSS Exploitation Probability

via FIRST.org ↗

11.0%probability of exploitation in next 30 days

Moderate Risk94th percentile+1.22%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

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.

Affected Products

3 products · 4 configurations

Application

acrobatadobe

≥ 24.0.0 && < 24.001.30360

range

Application

acrobat dcadobe

< 26.001.21411

range

Application

acrobat reader dcadobe

< 26.001.21411

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

azefzafyoussef/CVE-2026-34621

⭐ 21🍴 5Jun 2026

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2026-34621 in your stack?

O3 detects CVE-2026-34621 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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