CVE-2026-82398 py-pdf CVE debrief

Who should care

Defenders responsible for maintaining and securing systems that use the pypdf library should be aware of this vulnerability and take steps to update to version 6.15.0 or later. This includes reviewing and monitoring PDF processing workflows for potential performance issues and increased risk of denial-of-service attacks. Defenders should also prioritize updating to version 6.15.0 or later to prevent potential performance issues.

Why it matters

Defenders should prioritize updating to version 6.15.0 or later to prevent potential performance issues and increased risk of denial-of-service attacks.

• Potential performance issues when processing PDFs
• Increased risk of denial-of-service attacks

Technical summary

The pypdf library has a vulnerability that can cause long runtimes when processing specially crafted PDFs. The issue is caused by the read_until_whitespace function in pypdf/_utils.py, which can lead to quadratic processing costs for long non-whitespace input. This issue is fixed in version 6.15.0. The vulnerability can result in potential performance issues and increased risk of denial-of-service attacks. Defenders should prioritize updating to version 6.15.0 or later to prevent these issues. The CVE record was published on 2026-08-31T22:17:23.083Z and has not been modified since then.

Defensive priority

Defenders should prioritize updating to version 6.15.0 or later to prevent potential performance issues.

Recommended defensive actions

• Update to version 6.15.0 or later
• Review and monitor PDF processing workflows for potential performance issues
• 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
• 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 caused by the read_until_whitespace function in pypdf/_utils.py, which can lead to quadratic processing costs for long non-whitespace input. The function repeatedly performs immutable bytes concatenation in a one-byte loop, causing quadratic processing cost for the long non-whitespace input. This issue is fixed in version 6.15.0. The CVE record was published on 2026-08-31T22:17:23.083Z and has not been modified since then. 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.