CVE-2018-20312

Local privilege escalation via missing proxyDoAction opcode validation

Published Jan 7, 2021 · Updated Aug 5, 2024

Stack-based buffer overflow in Foxit Reader before 9.5 and PhantomPDF before 8.3.10 or 9.x before 9.5 allows local users to execute code. The PDF Printer proxyDoAction handler fails to validate user-supplied data for opcode 0x200000, allowing a large integer or long string to overrun its stack buffer. Exploitation requires low-privileged code execution on Windows and raises attacker-controlled code to medium integrity; malformed input can also disclose memory.

CVSS severity8.1
High
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack-based buffer overflow in Foxit Reader before 9.5 and PhantomPDF before 8.3.10 or 9.x before 9.5 allows local users to execute code. The PDF Printer proxyDoAction handler fails to validate user-supplied data for opcode 0x200000, allowing a large integer or long string to overrun its stack buffer. Exploitation requires low-privileged code execution on Windows and raises attacker-controlled code to medium integrity; malformed input can also disclose memory.

The record

CVE
CVE-2018-20312
Published
Jan 7, 2021
Updated
Aug 5, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-362, CWE-125, CWE-787, T1068
Attack vector
local
Privileges
authenticated

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 vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

4.5Source InciteCVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L
8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
6.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:P

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-125Out-of-bounds Read
CWE-787Out-of-bounds Write
T1068Exploitation for Privilege Escalation

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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