pypdf: Possible infinite loop when hitting EOF in standard xref table
Impact
An attacker who uses this vulnerability can craft a PDF that leads to an infinite loop. This requires an incomplete file that ends inside the xref table.
Patches
This has been fixed in pypdf==6.20.0..
Workarounds
If you cannot upgrade yet, consider applying the changes from PR #4170..
Notes
This has been reported through both the secure channel and as a public issue at #4169..
What to do
Upgrade to pypdf==6.20.0. or apply the changes from PR #4170..
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | pypdf | < 6.20.0 | 6.20.0 |
References
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-39mj-jf6j-2qj3
- https://github.com/py-pdf/pypdf/issues/4169
- https://github.com/py-pdf/pypdf/pull/4170
- https://github.com/py-pdf/pypdf/commit/37e1cd681744bac38b159f7e1c614eee8d639c58
- https://github.com/py-pdf/pypdf
- https://github.com/py-pdf/pypdf/releases/tag/6.20.0
- CVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-835- Platform
- Python (PyPI)
- Package
pypdf- Disclosed
- 21.10.2026
- Updated
- 21.10.2026 20:27
Sources and licenses · Edited or translated by DockRay; source rights and applicable licenses are retained.
OSV / GitHub Advisory Database - GHSA-39mj-jf6j-2qj3 - CC BY 4.0
Vulnerability history: pypdf
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 55
- First → latest
- 06.2023 10.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 10
- Medium 42
- Low 3
Disclosures per year
- 2023: 2
- 2024: 0
- 2025: 4
- 2026: 49
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