CVE-2026-119204 py-pdf CVE debrief

Who should care

Defenders responsible for systems using pypdf should assess exposure and prioritize upgrading to version 6.21.4 or later. This includes operators, platform administrators, vulnerability management teams, and security teams. They should review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance. They should also plan vendor-supported updates or mitigations through normal change control where exposure is A

Why it matters

Defenders should care about CVE-2026-119204 as it allows an attacker to craft a PDF leading to large memory usage in pypdf. This requires parsing the page tree with many shared resources. Upgrading to version 6.21.4 or later is recommended.

• Potential large memory usage leading to performance issues
• Need to verify and upgrade to version 6.21.4 or later

Technical summary

The vulnerability allows an attacker to craft a PDF that leads to large memory usage when parsing the page tree with many shared resources. This issue has been fixed in pypdf version 6.21.4. The vulnerability requires parsing the page tree with many shared resources, which can lead to performance issues. Defenders should prioritize upgrading to pypdf version 6.21.4 or later to prevent potential large memory usage issues. The official CVE Program record and NIST NVD detail page provide additional information on the vulnerability.

Defensive priority

Defenders should prioritize upgrading to pypdf version 6.21.4 or later to prevent potential large memory usage issues.

Recommended defensive actions

• Upgrade to pypdf version 6.21.4 or later
• Apply changes from PR #4290 if upgrade is not possible
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed
• 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

Evidence notes

The vulnerability allows an attacker to craft a PDF that leads to large memory usage when parsing the page tree with many shared resources. This issue has been fixed in pypdf version 6.21.4. The CVE record was published on 2026-10-30T23:13:01.000Z and has not been modified since then. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity. The official CVE Program record and NIST NVD detail page provide additional information.

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.