CVE-2026-103000 py-pdf CVE debrief

Who should care

Defenders responsible for applications that use pypdf for handling PDF documents and page labels should assess exposure and prioritize verification and remediation efforts. This includes reviewing applications that use pypdf, monitoring for potential memory consumption issues, and verifying and upgrading to pypdf version 6.19.0 or later. Defenders should also review compensating controls for exposed systems while remediation is scheduled and verified.

Why it matters

CVE-2026-103000 is a vulnerability in the pypdf library that can cause excessive memory consumption, potentially making applications that use pypdf unavailable. Defenders should prioritize verifying and upgrading to pypdf version 6.19.0 or later, especially in applications that handle PDF documents and page labels.

• Potential application unavailability due to excessive memory consumption
• Need for verification of pypdf version and potential upgrade to version 6.19.0 or later
• Monitoring for potential memory consumption issues with pypdf

Technical summary

The pypdf library, prior to version 6.19.0, is vulnerable to a crafted PDF that can cause it to generate excessively long page-label strings, leading to excessive memory consumption. This vulnerability can be triggered by unusually large alphabetical page-label values in a PDF, which can lead to memory consumption issues in applications using pypdf for handling PDF documents and page labels. The issue is fixed in pypdf version 6.19.0. Defenders should prioritize verifying and upgrading to pypdf version 6.19.0 or later, especially in applications that handle PDF documents and page labels.

Defensive priority

Defenders should prioritize verifying and upgrading to pypdf version 6.19.0 or later, especially in applications that handle PDF documents and page labels.

Recommended defensive actions

• Verify and upgrade to pypdf version 6.19.0 or later
• Review applications that use pypdf for handling PDF documents and page labels
• Monitor for potential memory consumption issues with pypdf
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and references to patches and advisories. The vulnerability is caused by a crafted PDF that can provide unusually large alphabetical page-label values. The issue is fixed in pypdf version 6.19.0. Defenders should verify and upgrade to pypdf version 6.19.0 or later, especially in applications that handle PDF documents and page labels. The CVE record was published on 2026-09-30T21:17:07.490Z and has not been modified since then.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.