medium5.3
CVE-2026-82398
pypdf: Inefficient handling of non-whitespace inputs in read_until_whitespace
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| pip | pypdf | < 6.15.0 | 6.15.0 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Pypdf Project | Pypdf | before 6.15.0 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-fc8x-2rww-xw9m
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-fc8x-2rww-xw9m
- https://nvd.nist.gov/vuln/detail/CVE-2026-82398
- https://github.com/py-pdf/pypdf/pull/3947
- https://github.com/py-pdf/pypdf/commit/4959848e057e37c218dccad7465259210923faaa
- https://github.com/py-pdf/pypdf/releases/tag/6.15.0