How severe is GHSA-g9xf-7f8q-9mcj?

No CVSS score has been assigned to GHSA-g9xf-7f8q-9mcj yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-g9xf-7f8q-9mcj?

GHSA-g9xf-7f8q-9mcj affects the following packages: pypdf (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-g9xf-7f8q-9mcj?

Update pypdf to 6.13.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g9xf-7f8q-9mcj is resolved across your whole dependency graph.

How do I detect GHSA-g9xf-7f8q-9mcj 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-g9xf-7f8q-9mcj 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-g9xf-7f8q-9mcj actively exploited in the wild?

No public exploit code has been indexed for GHSA-g9xf-7f8q-9mcj 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-g9xf-7f8q-9mcj?

GHSA-g9xf-7f8q-9mcj has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 5th 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-g9xf-7f8q-9mcj?

GHSA-g9xf-7f8q-9mcj 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-g9xf-7f8q-9mcj published, and has it been updated?

GHSA-g9xf-7f8q-9mcj was published on July 9, 2026 and was last updated on July 13, 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 processing threads/articles in writerGHSA-g9xf-7f8q-9mcj

Fix: py-pdf/pypdf#3839

GHSA-g9xf-7f8q-9mcj is a CWE-835 vulnerability in pypdf. A fix is available for pypdf — see the affected versions and patch details below.

Also known asCVE-2026-54651PYSEC-2026-3018

Published

Jul 9, 2026

Updated

Jul 13, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 24, 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-g9xf-7f8q-9mcj.

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs5th percentile — riskier than 5% 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 merging a file with threads/articles into a writer.

Patches

This has been fixed in pypdf==6.13.1.

Workarounds

If users cannot upgrade yet, consider applying the changes from PR #3839.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`pypdf`	all versions	6.13.1`pip install --upgrade 'pypdf==6.13.1'`

Affected Products

1 product · 1 configurations

Application

pypdfpypdf_project

< 6.13.1

range

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 6.13.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-g9xf-7f8q-9mcj 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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Red Hat rates this issue as Moderate severity (CVSS 5.9) because exploitation requires a specially crafted PDF containing thread/article objects to be processed by pypdf's merge functionality.

Workaround published by Red Hat

If PDF processing is required, implement processing timeouts and resource constraints (CPU/memory limits) to contain the impact of infinite loops. Running pypdf workloads in containerized processes with enforced resource limits provides defense-in-depth. Upgrading to pypdf >= 6.13.1 resolves this issue.

Source: Red Hat security advisory for GHSA-g9xf-7f8q-9mcj (CC BY 4.0)

Frequently Asked Questions

### Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. This requires merging a file with threads/articles into a writer. ### Patches This has been fixed in [pypdf==6.13.1](https://github.com/py-pdf/pypdf/releases/tag/6.13.1). ### Workarounds If users cannot upgrade yet, consider applying the changes from PR [#3839](https://github.com/py-pdf/pypdf/pull/3839).

O3 Security · Impact-Aware SCA

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