// impact
An attacker who uses this vulnerability can craft a PDF which leads to an infinite loop if parsecontentstream is executed. This infinite loop blocks the current process and can utilize a single core of the CPU by 100%. It does not affect memory usage. That is, for example, the case if the user extracted text from such a PDF.
Example Code and a PDF that causes the issue:
from pypdf import PdfReader
# https://objects.githubusercontent.com/github-production-repository-file-5c1aeb/3119517/11367871?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=AKIAIWNJYAX4CSVEH53A%2F20230627%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20230627T201018Z&X-Amz-Expires=300&X-Amz-Signature=d71c8fd9181c4875f0c04d563b6d32f1d4da6e7b2e6be2f14479ce4ecdc9c8b2&X-Amz-SignedHeaders=host&actor_id=1658117&key_id=0&repo_id=3119517&response-content-disposition=attachment%3Bfilename%3DMiFO_LFO_FEIS_NOA_Published.3.pdf&response-content-type=application%2Fpdf
reader = PdfReader("MiFO_LFO_FEIS_NOA_Published.3.pdf")
page = reader.pages[0]
page.extract_text()The issue was introduced with https://github.com/py-pdf/pypdf/pull/969
// patchesThe issue was fixed with https://github.com/py-pdf/pypdf/pull/1828
// workaroundsIt is recommended to upgrade to pypdf>=3.9.0. PyPDF2 users should migrate to pypdf.
If you cannot update your version of pypdf, you should modify pypdf/generic/datastructures.py:
OLD: while peek not in (b"\r", b"\n"): NEW: while peek not in (b"\r", b"\n", b""):
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Local
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High