pypdf's LZWDecode streams be manipulated to exhaust RAM

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 to align the default limit with the one for zlib.

Patches

This has been fixed in pypdf==6.4.0.

Workarounds

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