CVE-2026-113795: pypdf: Possible large memory usage for streams with multiple filters

Q: What applications are exposed to this issue?

Applications using pypdf versions prior to 6.20.0 are exposed when they access streams in attacker-crafted PDFs. The relevant streams contain either many filters or multiple filters that pass large amounts of data.

Q: What does an attacker need to do to trigger the problem?

An attacker needs to provide a crafted PDF and cause the application to access the affected stream. Successful triggering causes large memory consumption.

Q: What should be done if an immediate upgrade is not possible?

Apply the changes from PR #4173 as a workaround. The permanent fix is to upgrade pypdf to version 6.20.0.

Published Oct 21, 2026

Updated

Impact

An attacker who uses this vulnerability can craft a PDF which leads to large memory consumption. This requires accessing any stream with a large amount of filters or multiple filters which pass around large amounts of data.

Patches

This has been fixed in pypdf==6.20.0.

Workarounds

If you cannot upgrade yet, consider applying the changes from PR #4173.

Other sources

pypdf is a free and open-source pure-python PDF library. Prior to 6.20.0, accessing a crafted PDF stream with a large number of filters or multiple filters that pass around large amounts of data can cause large memory consumption. This issue is fixed in version 6.20.0.

— MITRE

Affected Software

2 affected componentsFixes available

pypi/pypdf<6.20.0

pip/pypdf<6.20.0

6.20.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade pip/pypdf to a version that resolves this vulnerability.
Fixed in 6.20.0
Upgrade
Upgrade pypdf to a version that resolves this vulnerability.
Fixed in 6.20.0
Compensating control
If upgrading is not yet possible, apply the changes from PR #4173.

Event History

Oct 21, 2026

CVE Published

via MITRE·04:01 PM

Data Sourced

via MITRE·04:01 PM

DescriptionWeakness

Advisory Published

via GitHub·04:48 PM

Data Sourced

via GitHub·04:48 PM

DescriptionWeaknessAffected Software

Frequently Asked Questions

What applications are exposed to this issue?

Applications using pypdf versions prior to 6.20.0 are exposed when they access streams in attacker-crafted PDFs. The relevant streams contain either many filters or multiple filters that pass large amounts of data.

What does an attacker need to do to trigger the problem?

An attacker needs to provide a crafted PDF and cause the application to access the affected stream. Successful triggering causes large memory consumption.

What should be done if an immediate upgrade is not possible?

Apply the changes from PR #4173 as a workaround. The permanent fix is to upgrade pypdf to version 6.20.0.

CVE-2026-113795: pypdf: Possible large memory usage for streams with multiple filters

Other sources

Affected Software

Remediation

Event History

Frequently Asked Questions

What applications are exposed to this issue?

What does an attacker need to do to trigger the problem?

What should be done if an immediate upgrade is not possible?

Company

Resources

Contact

Frequently Asked Questions

What applications are exposed to this issue?

What does an attacker need to do to trigger the problem?

What should be done if an immediate upgrade is not possible?