CVE-2018-18689Public exploitNetwork attack vector

Signed-content spoofing via unchecked ByteRange and xref

Published Jan 7, 2021 · Updated Aug 5, 2024

Signature verification bypass in multiple PDF viewers allows attackers to display altered document content as validly signed. The validation logic accepts manipulated /ByteRange values and cross-reference tables, allowing displayed objects to fall outside the authenticated byte ranges without invalidating the signature. Reachability requires a crafted PDF whose signing certificate is trusted by the viewer; the result is undetected document-content substitution rather than code execution.

CVSS severity5.3
Medium
EPSS probability3.69%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Signature verification bypass in multiple PDF viewers allows attackers to display altered document content as validly signed. The validation logic accepts manipulated /ByteRange values and cross-reference tables, allowing displayed objects to fall outside the authenticated byte ranges without invalidating the signature. Reachability requires a crafted PDF whose signing certificate is trusted by the viewer; the result is undetected document-content substitution rather than code execution.

The record

CVE
CVE-2018-18689
Published
Jan 7, 2021
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-347, T1036
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 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
5.3NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 exploitPublished

Weakness, pattern, technique

CWE-347Improper Verification of Cryptographic Signature
T1036Masquerading

Public exploit references

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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