CVE-2026-24688 pypdf has possible Infinite Loop when processing outlines/bookmarks
An attacker can cause a denial of service via an infinite loop in pypdf by crafting a malicious PDF with specific outlines or bookmarks.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-24688?
CVE-2026-24688 is a medium-severity denial of service vulnerability in Pypdf Project Pypdf, published on 27 Jan 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
pypdf is a free and open-source pure-python PDF library. An attacker who uses an infinite loop vulnerability that is present in versions prior to 6.6.2 can craft a PDF which leads to an infinite loop. This requires accessing the outlines/bookmarks. This has been fixed in pypdf 6.6.2. If projects cannot upgrade yet, consider applying the changes from PR #3610 manually.
Weakness: CWE-835
Which versions are affected by CVE-2026-24688?
3 open source packages ship an affected version, including pypdf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pypdf PyPI | All versions | 6.6.2 |
pypdf PyPI | All versions | 6.6.2 |
pypdf PyPI | All versions | 6.6.2 |
Linux distribution packages (1)
python-pypdf openSUSE:Tumbleweed | All versions | 6.6.2-1.1 |
Products include Pypdf Project Pypdf.
How do I fix CVE-2026-24688?
Upgrade pypdf to 6.6.2 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-2026-24688 being exploited?
There is no known exploitation of CVE-2026-24688 in the wild and no public exploit code.
Public exploit code: 2 proofs of concept on GitHub.
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 DEBIAN-CVE-2026-24688, GHSA-2q4j-m29v-hq73, PYSEC-2026-1827, ROOT-APP-PYPI-CVE-2026-24688, UBUNTU-CVE-2026-24688, openSUSE-SU-2026:10116-1.