CVE-2025-66019
highpriority · track · 0EPSS 0.004 · 33 %ileDEEURUUSEPSS · scored 2026-10-27
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.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.6–7.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (13)
Products and version ranges known to be affected.
advisories (3)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-1730Xerox FreeFlow Print Server: Mehrere Schwachstellen ermöglichen nicht spezifizierten AngriffDeutsch2026-05-28csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Xerox FreeFlow Print Server ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.
- GHSA-m449-cwjh-6pw7pypdf's LZWDecode streams be manipulated to exhaust RAM2025-11-24ghsa · osvUS
### 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 ```
- PYSEC-2026-1832pypdf's LZWDecode streams be manipulated to exhaust RAM2026-07-07vendor · osvUS
### 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 ```
also known as (7)
Other names and identifiers for this entity.
sources
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references (11)
External citations — patches, advisories, analysis.
- https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2cnnvd
- https://github.com/py-pdf/pypdf/releasesPatchcnnvd
- https://github.com/py-pdf/pypdf/releases/tag/6.4.0cnnvd
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7cnnvd
- https://github.com/py-pdf/pypdf/commit/96186725e5e6f237129a58a97cd19204a9ce40b2enisa_euvd
- https://github.com/py-pdf/pypdf/releases/tag/6.4.0enisa_euvd
- https://github.com/py-pdf/pypdf/security/advisories/GHSA-m449-cwjh-6pw7enisa_euvd
- https://aydinnyunus.github.io/2025/12/20/cve-2025-66019-pypdf-lzw-dos/nvd
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