### Impact
An attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing arrays and/or dictionaries with lots of elements.
### Patches
This has been fixed in [pypdf==6.21.0](https://github.com/py-pdf/pypdf/releases/tag/6.21.0).
### Workarounds
If you cannot upgrade yet, consider applying the changes from PR [#4218](https://github.com/py-pdf/pypdf/pull/4218).