CVE-2022-24859

### Impact An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop if the PyPDF2 user wrote the following code: ```python from PyPDF2 import PdfFileReader, PdfFileWriter from PyPDF2.pdf import ContentStream reader = PdfFileReader("malicious.pdf", strict=False) for page in reader.pages: ContentStream(page.getContents(), reader) ``` ### Patches [`PyPDF2==1.27.5`](https://pypi.org/project/PyPDF2) and later are patched. Credits to [Sebastian Krause](https://github.com/sekrause) for finding ([issue](https://github.com/py-pdf/PyPDF2/issues/329)) and fixing ([PR](https://github.com/py-pdf/PyPDF2/pull/740)) it.

PyPDF2 is an open source python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In versions prior to 1.27.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop if the PyPDF2 if the code attempts to get the content stream. The reason is that the last while-loop in `ContentStream._readInlineImage` only terminates when it finds the `EI` token, but never actually checks if the stream has already ended. This issue has been resolved in version `1.27.5`. Users unable to upgrade should validate and PDFs prior to iterating over their content stream.