CVE-2026-27025 py-pdf CVE debrief

Who should care

Defenders responsible for maintaining and securing systems and applications that use the pypdf library should be aware of this vulnerability and take steps to upgrade to version 6.7.1 or later to prevent potential performance issues. This includes operators, platform administrators, vulnerability management teams, and security teams who need to review and update affected systems and applications.

Why it matters

CVE-2026-27025 is a vulnerability in the pypdf library that can lead to performance issues. Defenders should prioritize upgrading to version 6.7.1 or later.

• Potential performance issues due to long runtimes and large memory consumption
• Need to upgrade to pypdf version 6.7.1 or later to prevent potential issues

Technical summary

The pypdf library is vulnerable to a performance issue that can lead to long runtimes and large memory consumption when parsing specific PDF files. This is due to the library's handling of the /ToUnicode entry of a font with unusually large values. The vulnerability requires parsing specific PDF files, which can lead to long runtimes and large memory consumption. The fix is available in pypdf version 6.7.1, which addresses the performance issue by properly handling the /ToUnicode entry of a font with unusually large values.

Defensive priority

Defenders should prioritize upgrading to pypdf version 6.7.1 or later to prevent potential performance issues.

Recommended defensive actions

• Upgrade to pypdf version 6.7.1 or later
• Review and update affected systems and applications
• Monitor for potential performance issues
• 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 NVD vulnerability detail page. The fix is available in pypdf version 6.7.1. The CVE record was published on 2026-02-20T22:16:28.850Z and has not been modified since then. The vulnerability can be triggered by parsing specific PDF files, which can lead to long runtimes and large memory consumption. The /ToUnicode entry of a font with unusually large values is the root cause of the issue.

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.