CVE-2021-34837

CVE-2021-34837 is a high-severity vulnerability in Foxit Pdf Reader with a CVSS 3.x base score of 7.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-416.

Key facts

• Severity: High (CVSS 3.x base score 7.8)
• CVSS v2: 6.8
• EPSS exploit prediction: 4% (89th percentile)
• Actively exploited: Not listed in CISA KEV
• Weakness: CWE-416
• Affected product: Foxit Pdf Reader
• Published: 2021-08-04
• Last modified: 2026-06-17

Description

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit PDF Reader 11.0.0.49893. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handling of Annotation objects. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-14018.

Frequently asked questions

What is CVE-2021-34837?

This vulnerability allows remote attackers to execute arbitrary code on affected installations of Foxit PDF Reader 11.0.0.49893. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The specific flaw exists within the handling of Annotation objects. The issue results from the lack of validating the existence of an object prior to performing operations on the object. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-14018.

How severe is CVE-2021-34837?

CVE-2021-34837 has a CVSS 3.x base score of 7.8, rated high severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-34837 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (89th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-34837?

CVE-2021-34837 primarily affects Foxit Pdf Reader. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-34837?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-34837 published?

CVE-2021-34837 was published on 2021-08-04 and last updated on 2026-06-17.

References

• https://www.foxit.com/support/security-bulletins.html
• https://www.zerodayinitiative.com/advisories/ZDI-21-919/

Affected products (3)

• cpe:2.3:a:foxit:pdf_reader:*:*:*:*:*:*:*:*
• cpe:2.3:a:foxitsoftware:pdf_editor:*:*:*:*:*:*:*:*
• cpe:2.3:a:foxitsoftware:pdf_editor:11.0.0.49893:*:*:*:*:*:*:*

More vulnerabilities in Foxit Pdf Reader

• CVE-2022-24955 — Critical (CVSS 9.8): Foxit PDF Reader before 11.2.1 and Foxit PDF Editor before 11.2.1 have an Uncontrolled Search Path Element for DLL…
• CVE-2022-24954 — Critical (CVSS 9.8): Foxit PDF Reader before 11.2.1 and Foxit PDF Editor before 11.2.1 have a Stack-Based Buffer Overflow related to XFA,…
• CVE-2021-38563 — Critical (CVSS 9.8): An issue was discovered in Foxit PDF Reader before 11.0.1 and PDF Editor before 11.0.1. It mishandles situations in…
• CVE-2025-13941 — High (CVSS 8.8): A local privilege escalation vulnerability exists in the Foxit PDF Reader/Editor Update Service. During plugin…
• CVE-2025-32451 — High (CVSS 8.8): A memory corruption vulnerability exists in Foxit Reader 2025.1.0.27937 due to the use of an uninitialized pointer. A…
• CVE-2024-49576 — High (CVSS 8.8): A use-after-free vulnerability exists in the way Foxit Reader 2024.3.0.26795 handles a checkbox CBF_Widget object. A…

All CVEs affecting Foxit Pdf Reader →

Other CWE-416 (Use After Free) vulnerabilities

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• CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
• CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
• CVE-2025-24085 — Critical (CVSS 10.0): A use after free issue was addressed with improved memory management. This issue is fixed in iOS 18.3 and iPadOS 18.3,…
• CVE-2024-43102 — Critical (CVSS 10.0): Concurrent removals of certain anonymous shared memory mappings by using the UMTX_SHM_DESTROY sub-request of…
• CVE-2021-32495 — Critical (CVSS 10.0): Radare2 has a use-after-free vulnerability in pyc parser's get_none_object function. Attacker can read freed memory…

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