CVE-2025-66019
Medium
Description
pypdf is a free and open-source pure-python PDF library. Prior to version 6.4.0, an attacker who uses this vulnerability can craft a PDF which leads to a memory usage of up to 1 GB per stream. This requires parsing the content stream of a page using the LZWDecode filter. This issue has been patched in version 6.4.0.
SeverityMedium
CVSS6.6
Exploit probability—
ProductPypdf
PublishedNov 26, 2025
First seenNov 26, 2025
How to fix
Update
- pypdf6.4.0 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| pypdfPyPI | v < 6.4.0 | 6.4.0 |
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