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CVE-2023-36807: pypdf: Malicious PDFs Can Cause CPU to Freeze

CVE-2023-36807 · published 3 years ago

Summary

A vulnerability in pypdf version 2.10.5 allows an attacker to create a PDF that can freeze the program, consuming 100% of a single CPU core. This is fixed in version 2.10.6. Upgrade to the latest version or apply a temporary fix if you can't update immediately.

What to do

Update mathieu fenniak pypdf2 to version 2.10.6.
Update debian pypdf2 to version 2.10.7-1.

Affected software

Ecosystem	Vendor	Product	Affected versions
pip	mathieu fenniak	pypdf2	2.10.5 Fix: upgrade to 2.10.6
–	pypdf_project	pypdf	2.10.5 `cpe:2.3:a:pypdf_project:pypdf:2.10.5:::::::*`
Debian:12	debian	pypdf2	< 2.10.7-1 Fix: upgrade to 2.10.7-1
–	py-pdf	pypdf	2.10.5 `cpe:2.3:a:py-pdf:pypdf:2.10.5:::::::*`

Original advisory text

Infinite Loop when reading malformed objects in pypdf

pypdf is a pure-python PDF library capable of splitting, merging, cropping, and transforming the pages of PDF files. In version 2.10.5 an attacker who uses this vulnerability can craft a PDF which leads to an infinite loop. 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 metadata from such a malformed PDF. Versions prior to 2.10.5 throw an error, but do not hang forever. This issue was fixed with https://github.com/py-pdf/pypdf/pull/1331 which has been included in release 2.10.6. Users are advised to upgrade. Users unable to upgrade should modify `PyPDF2/generic/_data_structures.py::read_object` to an an error throwing case. See GHSA-hm9v-vj3r-r55m for details.

References

https://github.com/py-pdf/pypdf/commit/e6531a25325e7e0174b6a1ba03b57320b5227f6b
https://github.com/advisories/GHSA-hm9v-vj3r-r55m
https://github.com/py-pdf/pypdf/issues/1329 Third Party Advisory
https://github.com/py-pdf/pypdf/pull/1331 Patch
https://github.com/py-pdf/pypdf/security/advisories/GHSA-hm9v-vj3r-r55m Vendor Advisory
https://security-tracker.debian.org/tracker/CVE-2023-36807 Vendor Advisory
https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/36xxx/CVE-2023-36807... Vendor Advisory
https://nvd.nist.gov/vuln/detail/CVE-2023-36807 Vendor Advisory

Fix within

Internet-facing 60 days

Internal At next upgrade

Not known to be exploited
Needs hands-on effort to exploit
Gives an attacker partial control

Severity

6.2 Medium

Exploitation

<1% chance of attack within 30 days

Type

CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')

Timeline

Published30 Jun 2023

Updated4 Nov 2026

First seen6 Mar 2026

Sources

GHSA-hm9v-vj3r-r55m · GHSA

CVE-2023-36807 · NVD

DEBIAN-CVE-2023-36807 · OSV

CVE-2023-36807 · OSV

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