CVE-2025-66019Medium▾ Sunlitpypdf's LZWDecode streams be manipulated to exhaust RAM
▾ Sunlit zone — Low / medium · no exploitation signal
impact 27.5 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Jul 8.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via OSV
0.3%
0.3% → 0.4%
Last analysed / modified upstream
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 to align the default limit with the one for zlib.
This has been fixed in pypdf==6.4.0.
If users cannot upgrade yet, use the line below to overwrite the default in their code:
pypdf.filters.LZW_MAX_OUTPUT_LENGTH = 75_000_000
pypdf < 6.4.0Upgrade to a patched release:
pypdf 6.4.0Connected by shared product, vendor, weakness, or advisory.
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