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pypdf: Possible infinite loop for TreeObject.insert_childGHSA-jp53-mhqp-8xcg

Fix: py-pdf/pypdf#3964

GHSA-jp53-mhqp-8xcg is a CWE-835 vulnerability in pypdf. A fix is available for pypdf — see the affected versions and patch details below.

Also known asCVE-2026-84309PYSEC-2026-3913
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-jp53-mhqp-8xcg.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk+0.01%
Lower risk than most CVEs8th percentile — riskier than 8% of all scored CVEsHighest risk
0.00%0.23%0.46%0.69%0.2%0.2%Oct 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected
🐍pypdf

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Impact

An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires a (usually writing) code path where TreeObject.insert_child is involved.

Patches

This has been fixed in pypdf==6.16.0.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #3964.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIpypdfall versions6.16.0pip install --upgrade 'pypdf==6.16.0'

Affected Products

1 product · 1 configurations
Application
pypdfpypdf_project
< 6.16.0
range

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pypdf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update pypdf to 6.16.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jp53-mhqp-8xcg is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires a (usually writing) code path where `TreeObject.insert_child` is involved. ### Patches This has been fixed in [pypdf==6.16.0](https://github.com/py-pdf/pypdf/releases/tag/6.16.0). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#3964](https://github.com/py-pdf/pypdf/pull/3964).
O3 Security · Impact-Aware SCA

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pypdf: Possible infinite loop for TreeObject.insert_child