CVE-2026-33699 pypdf: Possible infinite loop during recovery attempts in DictionaryObject.read_from_stream
An attacker can cause a denial of service via infinite loop in pypdf when processing crafted PDFs in non-strict mode.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33699?
CVE-2026-33699 is a medium-severity denial of service vulnerability in Pypdf Project Pypdf, published on 26 Mar 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. Versions prior to 6.9.2 have a vulnerability in which an attacker can craft a PDF which leads to an infinite loop. This requires reading a file in non-strict mode. This has been fixed in pypdf 6.9.2. If users cannot upgrade yet, consider applying the changes from the patch manually.
Weakness: CWE-835
Which versions are affected by CVE-2026-33699?
3 open source packages ship an affected version, including pypdf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pypdf PyPI | All versions | 6.9.2 |
pypdf PyPI | All versions | 6.9.2 |
pypdf PyPI | All versions | 6.9.2 |
Linux distribution packages (1)
python-pypdf openSUSE:Tumbleweed | All versions | 6.9.2-1.1 |
Products include Pypdf Project Pypdf.
How do I fix CVE-2026-33699?
Upgrade pypdf to 6.9.2 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-2026-33699 being exploited?
There is no known exploitation of CVE-2026-33699 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-2026-33699, ECHO-8bab-aae8-22d2, GHSA-87mj-5ggw-8qc3, MINI-cf8m-8mr4-c75c, MINI-p69r-v447-2x93, PYSEC-2026-3012 and 3 more.