CVE-2024-56139Public exploit

Converter crash via invalid font-state write

Published Dec 17, 2024 · Updated Dec 20, 2024

Stack-based buffer overflow in Leonhad PDFTools 0.5.0 and earlier allows attackers to crash the converter with a crafted ePUB file. During page generation, Glyph::Execute passes malformed font state through Context::SetCurrentFont to Font::SetSize, which writes through a near-null address. Processing an untrusted ePUB file is required; the demonstrated consequence is a process crash, with no grounded confidentiality impact.

CVSS severity6.9
Medium
EPSS probability0.39%
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 Leonhad PDFTools 0.5.0 and earlier allows attackers to crash the converter with a crafted ePUB file. During page generation, Glyph::Execute passes malformed font state through Context::SetCurrentFont to Font::SetSize, which writes through a near-null address. Processing an untrusted ePUB file is required; the demonstrated consequence is a process crash, with no grounded confidentiality impact.

The record

CVE
CVE-2024-56139
Published
Dec 17, 2024
Updated
Dec 20, 2024
Vendor
Leonhad
Product
PDFTools
Classifications
CWE-121, T1499.004
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 17, 2024CVE publishedPublication date reported by the CVE source.
  2. Dec 20, 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?

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

  1. Affected versionversion=<= 0.5.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Leonhad · PDFToolsversion=<= 0.5.0

Published CVSS scores

4.0LeonhadCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
6.9GitHub, Inc.CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA: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.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
T1499.004Endpoint Denial of Service: Application or System Exploitation

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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