CVE-2026-71852 pypdf: Possible long runtimes/large memory usage for large CID font width ranges
Attackers can cause denial of service via resource exhaustion in pypdf by crafting PDFs with large CID font width ranges.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-71852?
CVE-2026-71852 is a medium-severity denial of service vulnerability in Pypdf Project Pypdf, published on 7 Aug 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
pypdf is a free and open-source pure-python PDF library. Prior to 6.15.0, a crafted PDF can cause long runtimes and large memory consumption when pypdf/_font.py function Font._collect_cid_character_widths expands unusually large CID font /W width ranges or excessive width entries during text extraction. This issue is fixed in 6.15.0.
Weakness: CWE-834
Which versions are affected by CVE-2026-71852?
3 open source packages ship an affected version, including pypdf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pypdf PyPI | All versions | 6.15.0 |
pypdf PyPI | All versions | 6.15.0 |
pypdf PyPI | All versions | 6.15.0 |
Products include Pypdf Project Pypdf.
How do I fix CVE-2026-71852?
Upgrade pypdf to 6.15.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-71852 being exploited?
There is no known exploitation of CVE-2026-71852 in the wild and no public exploit code.
Other vulnerabilities in Pypdf Project Pypdf
- CVE-2026-102993 pypdf: Possible large memory usage when retrieving Roman page labels
- CVE-2026-102994 pypdf: Possible long runtimes/large memory usage when parsing indirect objects
- CVE-2026-102995 pypdf: Possible large memory usage for large /ToUnicode streams (Follow-up 2)
- CVE-2026-102996 pypdf: Possible large memory usage when parsing font data
- CVE-2026-102997 pypdf: Possible long runtimes for partially malformed FlateDecode streams (Follow-up)
Sources
Also known as CLEANSTART-2026-YL68876, DEBIAN-CVE-2026-71852, ECHO-d342-478d-0776, GHSA-fwg2-594c-jp42, MINI-26v6-65rj-4p8h, MINI-2j9m-5jfg-8296 and 15 more.