Prototype Pollution Vulnerability in Adobe Acrobat Reader
CVE-2026-34621

8.6HIGH

Key Information:

Vendor: Adobe
Status: Acrobat Reader
Vendor: CVE Published:; 11 April 2026

Badges

📈 Trended📈 Score: 6,780💰 Ransomware👾 Exploit Exists🟡 Public PoC🦅 CISA Reported📰 News Worthy

What is CVE-2026-34621?

CVE-2026-34621 is a significant vulnerability found in Adobe Acrobat Reader, a widely used application for viewing, creating, and editing PDF documents. This vulnerability stems from an improperly controlled modification of object prototype attributes, known as Prototype Pollution. If successfully exploited, it allows for arbitrary code execution within the context of the user running the application. To trigger this vulnerability, a user must interact with the system by opening a malicious PDF file, which poses a risk particularly in environments where users may inadvertently open untrusted documents. Given the widespread use of Acrobat Reader in organizations, this vulnerability presents a considerable threat, as it can lead to unauthorized access and manipulation of sensitive data or system resources.

Potential impact of CVE-2026-34621

Arbitrary Code Execution: The most critical impact of this vulnerability is the potential for arbitrary code execution. Attackers can exploit this flaw to execute malicious code in the context of the current user, which can lead to a complete compromise of the individual's session and potentially the wider network.
Data Breach and Sensitive Information Exposure: Successful exploitation of this vulnerability can lead to unauthorized access to sensitive information stored on the affected machine. This could result in data theft, integrity violations, and exposure of confidential organizational data to malicious actors.
Increased Risk of Malware Infection: By allowing arbitrary code execution, this vulnerability enables the installation of various forms of malware, including ransomware. While direct exploitations of this vulnerability have not been reported, the potential for creating further vulnerabilities or backdoors in an organization's systems is significant, increasing overall cybersecurity risk.

CISA has reported CVE-2026-34621

CISA provides regional cyber and physical services to support security and resilience across the United States. CISA monitor the most dangerious vulnerabilities and have identifed CVE-2026-34621 as being exploited but is not known by the CISA to be used in ransomware campaigns. This is subject to change at pace as recent news articles suggest the vulnerability is being used by ransomware groups.

The CISA's recommendation 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.

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Affected Version(s)

Acrobat Reader 0 <= 26.001.21367

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

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Created by NULL200OK

News Articles

Help Net Security

CVE-2026-34621 CVE-2026-39813

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