dbcve.org
Stack-based Buffer OverflowWeakness · CWE-121

CVE-2024-56139

MEDIUM · 6.9 CVSS v4.0 Published 2024-12-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
78/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
pdftools is a high level tools to convert PDF files to ePUB formats. In versions up to and including 0.5.0 maliciously crafted epub files can cause a stack overflow leading to a crash. This issue has not yet been addressed and users are advised to avoid untrusted input to their systems.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

pdftools versions up to 0.5.0 suffer from a stack overflow vulnerability when parsing maliciously crafted epub files, leading to a denial of service (crash). The vulnerability occurs during epub file processing and is exploitable via untrusted input.

MitigationAvoid processing untrusted epub files with pdftools until a patch is available. Implement input validation and resource limits on epub file processing to mitigate the risk.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if pdftools package is installed
    Run 'pip show pdftools' or check your package manager for the pdftools package and note the installed version number
    Affected if pdftools is installed and the version is 0.5.0 or any earlier version
  2. Compare installed version to affected range
    The vulnerability affects versions up to and including 0.5.0. If your version is 0.5.0 or lower, you are in the affected range
    Affected if The installed version is 0.5.0 or lower (any version from 0.1.0 through 0.5.0)
  3. Identify epub file processing usage
    Search your codebase, scripts, or application logs for calls to pdftools functions that handle epub files (such as epubs, epub2pdf, or similar epub-related functions)
    Affected if Your application or workflow uses pdftools to process epub files from any source
  4. Check for untrusted input handling
    Review whether pdftools processes epub files from untrusted or external sources, such as user uploads, web requests, or files from unknown origins
    Affected if pdftools processes epub files from untrusted or external sources

You are affected if pdftools version 0.5.0 or lower is installed AND your system uses pdftools to parse epub files, particularly from untrusted sources.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Avoid processing untrusted epub files with pdftools until a patch is available. Implement input validation and resource limits on epub file processing to mitigate the risk.

Recommended fix High confidence
  1. Do not process untrusted or maliciously crafted EPUB files with pdftools
  2. If pdftools must be used, run it in an isolated environment such as a container or VM with limited privileges
  3. Implement input validation to ensure only expected and trusted EPUB files are processed
  4. Consider using alternative PDF to EPUB conversion tools that receive security updates

Generated from the published advisory — verify against the referenced sources before acting.

Have this fixed Scoped from the published advisory
  • Consultation4.0 h
  • Implementation12.0 h
  • Testing6.0 h
  • Review / QA4.0 h
26.0 hours of engineering $4,580
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-56139 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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