CVE-2026-22691 py-pdf CVE debrief

Who should care

Defenders responsible for PDF processing systems using the pypdf library should assess exposure and prioritize updating to version 6.6.0 or later. The vulnerability can lead to denial of service (DoS) due to excessive resource consumption. Defenders should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

Why it matters

Defenders should care about CVE-2026-22691 because it can cause long runtimes for malformed startxref entries in PDF files, potentially leading to denial of service (DoS) due to excessive resource consumption. The vulnerability affects the non-strict reading mode of the pypdf library and has been patched in version 6.6.0. Defenders responsible for PDF processing systems using the pypdf library should assess exposure and prioritize updating to version 6.6.0 or later.

• Long runtimes for PDF processing
• Potential denial of service (DoS) due to excessive resource consumption

Technical summary

The pypdf library has a vulnerability that can cause long runtimes for malformed startxref entries in PDF files. This issue affects the non-strict reading mode and has been patched in version 6.6.0. The vulnerability can lead to denial of service (DoS) due to excessive resource consumption. The patch is available in version 6.6.0 of the pypdf library. Defenders should prioritize updating to version 6.6.0 or later to mitigate this vulnerability. The vulnerability is described in the CVE record and the NVD vulnerability detail page.

Defensive priority

Defenders should prioritize updating to version 6.6.0 or later to mitigate this vulnerability.

Recommended defensive actions

• Update to pypdf version 6.6.0 or later
• Review PDF files for potential malicious startxref entries
• Monitor for long runtimes in PDF processing
• 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 vulnerability is described in the CVE record and the NVD vulnerability detail page. The patch is available in version 6.6.0 of the pypdf library. Defenders should verify the affected scope and severity, and review the supplied official advisory or CVE record to validate vendor guidance. The vulnerability affects the non-strict reading mode of the pypdf library.

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.