Is CVE-2026-103000 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-103000 being exploited in the wild.

How severe is CVE-2026-103000?

High severity, with a CVSS score of 4, published 30 September 2026.

Which products and versions are affected?

Py-Pdf Pypdf prior to 6.19.0; pypdf (PyPI) < 6.19.0, ECOSYSTEM:introduced=0,fixed=6.19.0.

Is there a fix for CVE-2026-103000?

Yes. pypdf (PyPI): upgrade to 6.19.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-103000 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-103000?

Check whether you run Py-Pdf Pypdf or pypdf (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-103000: pypdf denial of service in alphabetical page label processing

Q: Is there a fix for CVE-2026-103000?

Yes. pypdf (PyPI): upgrade to 6.19.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-103000 attacked?

It is attacked over the network, in a software library.

Q: Am I affected by CVE-2026-103000?

Check whether you run Py-Pdf Pypdf or pypdf (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-103000 · Severity: high · CVSS 4 · Published 2026-09-30

pypdf is a Python library for reading and manipulating PDF documents. A specially crafted PDF file with extremely large alphabetical page-label values can cause the library to generate excessively long strings that consume large amounts of memory, potentially causing an application using pypdf to become unavailable or crash.

Technologies: Py-Pdf Pypdf, pypdf (PyPI). Vendors: Py-Pdf, PyPI.

Quick answers

Is CVE-2026-103000 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-103000 being exploited in the wild.
How severe is CVE-2026-103000?: High severity, with a CVSS score of 4, published 30 September 2026.
Which products and versions are affected?: Py-Pdf Pypdf prior to 6.19.0; pypdf (PyPI) < 6.19.0, ECOSYSTEM:introduced=0,fixed=6.19.0.
Is there a fix for CVE-2026-103000?: Yes. pypdf (PyPI): upgrade to 6.19.0 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-103000 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-103000?: Check whether you run Py-Pdf Pypdf or pypdf (PyPI) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

pypdf (PyPI): upgrade to 6.19.0 or later
```
pip install "pypdf>=6.19.0"
```

Technical details

The vulnerability exists in pypdf/_page_labels.py where alphabetical page label values are not properly constrained, allowing a crafted PDF to trigger generation of unreasonably long strings. An unauthenticated attacker can trigger this by providing a malicious PDF file that an application processes. The vulnerability is memory exhaustion leading to denial of service; a fix is available in version 6.19.0.

Affected products

py-pdf pypdf prior to 6.19.0

Identifiers

CVE-2026-103000
GHSA-w23x-9jrw-r45c
PYSEC-2026-4160

Timeline

2026-09-16: patched: Fix merged in pull request #4096
2026-09-30: disclosed

References

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