GHSA-m449-cwjh-6pw7
pypdf's LZWDecode streams be manipulated to exhaust RAM
At a glance
- Published
- Updated
- CVE
- CVE-2025-66019
- Aliases
- PYSEC-2026-1832
- CVSS_V4
- CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U
Description
### Impact 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 is a follow up to [GHSA-jfx9-29x2-rv3j](https://github.com/py-pdf/pypdf/security/advisories/GHSA-jfx9-29x2-rv3j) to align the default limit with the one for *zlib*. ### Patches This has been fixed in [pypdf==6.4.0](https://github.com/py-pdf/pypdf/releases/tag/6.4.0). ### Workarounds If users cannot upgrade yet, use the line below to overwrite the default in their code: ```python pypdf.filters.LZW_MAX_OUTPUT_LENGTH = 75_000_000 ```
Affected packages
| Package | Versions |
|---|---|
| PyPI · pypdf | introduced 0, fixed 6.4.0 |
References
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-jfx9-29x2-rv3j WEB
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7 WEB
- https://nvd.nist.gov/vuln/detail/CVE-2025-66019 ADVISORY
- https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2 WEB
- https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos WEB
- https://github.com/py-pdf/pypdf PACKAGE
- https://github.com/py-pdf/pypdf/releases/tag/6.4.0 WEB
Sources
| Source | Licence |
|---|---|
| OSV.dev | CC-BY 4.0 — GitHub Advisory Database |