CVE-2026-82398: CWE-407: Inefficient Algorithmic Complexity in py-pdf pypdf
Description
CVE-2026-82398 is an inefficient algorithmic complexity vulnerability in the py-pdf pypdf library. An attacker can craft a specially designed PDF that triggers long runtimes by causing the function read_until_whitespace to process input lacking whitespace for an extended period. This can lead to performance degradation when parsing such PDFs. The issue has been fixed in pypdf version 6.15.0. Users unable to upgrade immediately may apply the changes from pull request #3947 as a workaround.
CVSS v4.0
Score 6.9medium
Affected software
py-pdf
pypdf
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability CVE-2026-82398 in py-pdf pypdf is classified as CWE-407 (inefficient algorithmic complexity). It occurs when the read_until_whitespace function is called with input that contains no whitespace for a long time, causing excessive processing time. This can be exploited by an attacker crafting a malicious PDF to induce long runtimes in the library. The problem has been addressed and fixed in pypdf version 6.15.0. A workaround is available by applying the changes from PR #3947 if upgrading is not immediately possible.
Potential Impact
An attacker can cause the pypdf library to consume excessive processing time by providing a crafted PDF file that triggers inefficient parsing behavior. This results in long runtimes, potentially leading to denial of service or degraded performance in applications using the vulnerable versions of pypdf. There is no indication of privilege escalation, data leakage, or code execution from the provided information.
Mitigation Recommendations
Upgrade to pypdf version 6.15.0 or later, where this vulnerability is fixed. If upgrading is not feasible immediately, apply the changes from pull request #3947 as a temporary workaround to mitigate the issue.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-28T22:00:43.512Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6a95f7a8acd9273b49a2944b
Added to database: 08/31/2026, 21:52:40 UTC
Last enriched: 10/03/2026, 17:25:49 UTC
Last updated: 10/15/2026, 06:48:19 UTC
Views: 96
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.