CVE-2026-41168 pypdf has possible long runtimes for wrong size values in cross-reference and object streams
An attacker can cause long runtimes and denial of service in pypdf by crafting PDFs with invalid cross-reference or object stream size values.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-41168?
CVE-2026-41168 is a medium-severity denial of service vulnerability in Pypdf Project Pypdf, published on 22 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
pypdf is a free and open-source pure-python PDF library. An attacker who uses a vulnerability present in versions prior to 6.10.1 can craft a PDF which leads to long runtimes. This requires cross-reference streams with wrong large `/Size` values or object streams with wrong large `/N` values. This has been fixed in pypdf 6.10.1. As a workaround, one may apply the changes from the patch manually.
Weakness: CWE-834
Which versions are affected by CVE-2026-41168?
3 open source packages ship an affected version, including pypdf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pypdf PyPI | All versions | 6.10.1 |
pypdf PyPI | All versions | 6.10.1 |
pypdf PyPI | All versions | 6.10.1 |
Products include Pypdf Project Pypdf.
How do I fix CVE-2026-41168?
Upgrade pypdf to 6.10.1 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-2026-41168 being exploited?
There is no known exploitation of CVE-2026-41168 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 DEBIAN-CVE-2026-41168, ECHO-9559-f7c7-5c47, GHSA-jj6c-8h6c-hppx, MINI-6mqp-4fpg-m6w3, MINI-x7pc-fpm7-8c36, PYSEC-2026-3021 and 3 more.