CVE-2026-41312 pypdf: Manipulated FlateDecode predictor parameters can exhaust RAM
An attacker can cause RAM exhaustion and denial of service by crafting a PDF with manipulated FlateDecode predictor parameters in pypdf.
- 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-2026-41312?
CVE-2026-41312 is a medium-severity denial of service vulnerability in Pypdf Project Pypdf, published on 22 Apr 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. An attacker who uses a vulnerability present in versions prior to 6.10.2 can craft a PDF which leads to the RAM being exhausted. This requires accessing a stream compressed using `/FlateDecode` with a `/Predictor` unequal 1 and large predictor parameters. This has been fixed in pypdf 6.10.2. As a workaround, one may apply the changes from the patch manually.
Weakness: CWE-789
Which versions are affected by CVE-2026-41312?
3 open source packages ship an affected version, including pypdf. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
pypdf PyPI | All versions | 6.10.2 |
pypdf PyPI | All versions | 6.10.2 |
pypdf PyPI | All versions | 6.10.2 |
Products include Pypdf Project Pypdf.
How do I fix CVE-2026-41312?
Upgrade pypdf to 6.10.2 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-2026-41312 being exploited?
There is no known exploitation of CVE-2026-41312 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-2026-41312, ECHO-6000-bce7-d021, GHSA-7gw9-cf7v-778f, MINI-w9h7-fhjr-4w44, MINI-wm96-w439-mx43, MINI-xvmj-78ph-fxv7 and 4 more.