CVE-2021-3407

Memory corruption via zero-numbered trailer object

Published Feb 23, 2021 · Updated Feb 13, 2025

Double free in MuPDF 1.18.0 allows attackers to corrupt process memory through a malformed PDF during linearization. The PDF parser accepts an illegal trailer object numbered zero, overwriting the reserved free object and causing the same object to be released twice. A local user must process the crafted document; the bounded result is a crash or other memory corruption within the MuPDF process.

CVSS severity7.8
High
EPSS probability50.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Double free in MuPDF 1.18.0 allows attackers to corrupt process memory through a malformed PDF during linearization. The PDF parser accepts an illegal trailer object numbered zero, overwriting the reserved free object and causing the same object to be released twice. A local user must process the crafted document; the bounded result is a crash or other memory corruption within the MuPDF process.

The record

CVE
CVE-2021-3407
Published
Feb 23, 2021
Updated
Feb 13, 2025
Vendor
Artifex Software, Inc.
Product
MuPDF
Classifications
CWE-415, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Feb 13, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.18.0
  2. Affected versionversion=mupdf 1.18.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Artifex Software, Inc. · MuPDFversion=0 <1.18.0; version=mupdf 1.18.0

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
7.8CISA-ADPCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:N/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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-415Double Free
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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