How severe is GHSA-9mx8-4j7g-633p?

No CVSS score has been assigned to GHSA-9mx8-4j7g-633p yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-9mx8-4j7g-633p?

GHSA-9mx8-4j7g-633p affects the following packages: pypdf (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-9mx8-4j7g-633p?

Update pypdf to 6.20.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9mx8-4j7g-633p is resolved across your whole dependency graph.

How do I detect GHSA-9mx8-4j7g-633p in my PyPI dependencies?

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.

How do I mitigate GHSA-9mx8-4j7g-633p if there is no patch (or I can't update yet)?

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.

Is GHSA-9mx8-4j7g-633p actively exploited in the wild?

No public exploit code has been indexed for GHSA-9mx8-4j7g-633p yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-9mx8-4j7g-633p?

GHSA-9mx8-4j7g-633p has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 39th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-9mx8-4j7g-633p?

GHSA-9mx8-4j7g-633p is classified as CWE-835 (CWE-835). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-9mx8-4j7g-633p published, and has it been updated?

GHSA-9mx8-4j7g-633p was published on October 21, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

pypdf: Possible infinite loop when removing tree itemsGHSA-9mx8-4j7g-633p

Fix: py-pdf/pypdf#4188

GHSA-9mx8-4j7g-633p is a CWE-835 vulnerability in pypdf. A fix is available for pypdf — see the affected versions and patch details below.

Also known asCVE-2026-113793

Published

Oct 21, 2026

Updated

Oct 21, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs39th percentile — riskier than 39% of all scored CVEsHighest risk

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 removing an object from a tree, for example an outline item.

Patches

This has been fixed in pypdf==6.20.1.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #4188.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`pypdf`	all versions	6.20.1`pip install --upgrade 'pypdf==6.20.1'`

Detection & mitigation playbook

Open-source dependency

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.
Fix
Update pypdf to 6.20.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9mx8-4j7g-633p is resolved across your whole dependency graph.
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 removing an object from a tree, for example an outline item. ### Patches This has been fixed in [pypdf==6.20.1](https://github.com/py-pdf/pypdf/releases/tag/6.20.1). ### Workarounds If you cannot upgrade yet, consider applying the changes from PR [#4188](https://github.com/py-pdf/pypdf/pull/4188).

O3 Security · Impact-Aware SCA

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