CVE-2020-13803Network attack vector

Document trust bypass via incorrect signature validation

Published Jun 4, 2020 · Updated Aug 4, 2024

Signature validation bypass in Foxit PhantomPDF Mac and Foxit Reader for Mac before 4.0 allows attackers to make altered PDFs appear valid. The signature validator returns an incorrect result for maliciously modified PDFs or files containing non-standard signatures. Exploitation requires a crafted signed PDF to reach the validation workflow; the result misrepresents document authenticity without reported code execution.

CVSS severity7.5
High
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Signature validation bypass in Foxit PhantomPDF Mac and Foxit Reader for Mac before 4.0 allows attackers to make altered PDFs appear valid. The signature validator returns an incorrect result for maliciously modified PDFs or files containing non-standard signatures. Exploitation requires a crafted signed PDF to reach the validation workflow; the result misrepresents document authenticity without reported code execution.

The record

CVE
CVE-2020-13803
Published
Jun 4, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, CAPEC-463, CAPEC-475, T1036
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 4, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:P/I:N/A:N
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
CAPEC-463Padding Oracle Crypto Attack
CAPEC-475Signature Spoofing by Improper Validation
T1036Masquerading

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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