CVE-2026-82398
Medium
Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, an attacker can craft a PDF that causes long runtimes when the pypdf/_utils.py function read_until_whitespace reads a stream containing a long run of bytes without whitespace. 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.
SeverityMedium
CVSS5.3
Exploit probability—
ProductPypdf
PublishedAug 31, 2026
First seenAug 31, 2026
Weakness typeCWE-407CWE-407
How to fix
Update
- pypdf_project pypdf6.15.0 or later
- pypdf6.15.0 or later
- py-pdf pypdf6.15.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| pypdf_project pypdf | v < 6.15.0 | 6.15.0 |
| pypdfPyPI | v < 6.15.0 | 6.15.0 |
| py-pdf pypdf | v < 6.15.0 | 6.15.0 |
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