CVE-2023-36807 - CVE House
Back to Database
Status published Medium CVE-2023-36807

Infinite Loop when reading malformed objects in pypdf

Vulnerability Description

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.

Impact Analysis

Refer to official advisory for detailed impact metrics.

Remediation

Ensure systems are updated to the latest vendor-supplied patch levels.

THREAT MONITOR

Am I Vulnerable?

Launch our assessment wizard to check if your infrastructure is exposed to • CVE-2023-36807

Credits & Attribution

No credits recorded in the NVD database.

References

More from py-pdf

View All →
CVE-2025-66019
pypdf manipulated LZWDecode streams can exhaust RAM
Medium 6.6
CVE-2025-62708
pypdf manipulated LZWDecode streams can exhaust RAM
Medium 6.6
CVE-2025-62707
pypdf affected by possible infinite loop when reading DCT inline images without EOF marker
Medium 6.6
CVE-2025-55197
pypdf's Manipulated FlateDecode streams can exhaust RAM
Medium 6.6
CVE-2023-46250
pypdf possible Infinite Loop when PdfWriter(clone_from) is used with a PDF
Medium 5.1

Affected Vendor

Affected Software

pypdf
Vulnerable Versions:
2.10.5

Timeline

Official Publish: June 30th, 2023
Last Modified: November 6th, 2024
Added to House: July 22nd, 2026

CVSS Vectors

V3: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Weaknesses (CWE)

CWE-835

MITRE ATT&CK TTPs

T1499 Endpoint Denial of Service
Impact
T1190 Exploit Public-Facing Application
Initial Access
T1059 Command and Scripting Interpreter
Execution
T1562 Impair Defenses
Defense Evasion
T1485 Data Destruction
Impact