Improper Handling of Highly Compressed Data (Data Amplification) Affecting pypdf package, versions [,6.4.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PYTHON-PYPDF-14105065
- published25 Nov 2025
- disclosed24 Nov 2025
- creditYunus AYDIN
Introduced: 24 Nov 2025
CVE-2025-66019 (opens in a new tab)How to fix?
Upgrade pypdf to version 6.4.0 or higher.
Overview
pypdf is an A pure-python PDF library capable of splitting, merging, cropping, and transforming PDF files
Affected versions of this package are vulnerable to Improper Handling of Highly Compressed Data (Data Amplification) via the LZWDecode process. An attacker can exhaust system memory by crafting a PDF that triggers excessive memory allocation during content stream parsing. This is only exploitable if the content stream of a page uses the LZWDecode filter.
Workaround
This vulnerability can be mitigated by setting pypdf.filters.LZW_MAX_OUTPUT_LENGTH = 75_000_000.