Manipulated inline images can cause Infinite Loop in PyPDF2GHSA-xcjx-m2pj-8g79
MEDIUMFix: py-pdf/PyPDF2#740GHSA-xcjx-m2pj-8g79 is a medium-severity (CVSS 6.2) CWE-835 vulnerability in pypdf2. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. A fix is available for pypdf2 — see the affected versions and patch details below.
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for GHSA-xcjx-m2pj-8g79.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
pypdf2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
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:
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 and later are patched.
Credits to Sebastian Krause for finding (issue) and fixing (PR) it.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pypdf2 | all versions | 1.27.5pip install --upgrade 'pypdf2==1.27.5' |
Affected Products
debian linuxdebianpypdf2pypdf2_projectResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pypdf2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pypdf2 to 1.27.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xcjx-m2pj-8g79 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
Frequently Asked Questions
Is GHSA-xcjx-m2pj-8g79 in your dependencies?
Find it across PyPI, including transitive dependencies.