CVE-2026-102997
High
Description
pypdf is a free and open-source pure-python PDF library. Prior to 6.18.1, a crafted PDF containing a partially malformed /FlateDecode stream with padded data can force pypdf/filters.py to use inefficient byte-by-byte decompression while the earlier recovery counter fails to advance for bytes that successfully decode, causing long runtimes and application unavailability. This is a residual issue after the malformed FlateDecode recovery fix. This issue is fixed in version 6.18.1.
SeverityHigh
CVSS7.5
Exploit probability—
ProductPypdf
PublishedSep 30, 2026
First seenSep 30, 2026
How to fix
Update
- pypdf_project pypdf6.18.1 or later
- pypdf6.18.1 or later
- py-pdf pypdf6.18.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| pypdf_project pypdf | v < 6.18.1 | 6.18.1 |
| pypdfPyPI | v < 6.18.1 | 6.18.1 |
| py-pdf pypdf | v < 6.18.1 | 6.18.1 |
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