Inefficient Algorithmic Complexity Affecting pypdf package, versions [,6.18.1)
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-20415639
- published3 Oct 2026
- disclosed1 Oct 2026
- creditgeoffrey-diederichs
Introduced: 1 Oct 2026
NewCVE-2026-102997 (opens in a new tab)How to fix?
Upgrade pypdf to version 6.18.1 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 Inefficient Algorithmic Complexity via the decompress function in pypdf/filters.py when processing a /FlateDecode stream. The recovery path iterates byte-by-byte over input data, and the limit that was intended to abort excessive iteration only triggered on bytes that caused a zlib.error. For valid but non-conforming data such as a GZIP-prefixed stream, every byte decodes without error, so the limit never fires and the slow byte-by-byte loop runs to completion over arbitrarily large input, causing a severe performance degradation that crashes or hangs the process.