What is CVE-2026-28351?

CVE-2026-28351 is a medium-severity vulnerability in Py-Pdf Pypdf, classified under Uncontrolled Resource Consumption. CVSS score: 5.3/10. Published 2026-02-27.

How severe is CVE-2026-28351?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Resource exhaustion in Py-Pdf Pypdf

CVE-2026-28351

pypdf is a free and open-source pure-python PDF library. Prior to version 6.7.4, an attacker who uses this vulnerability can craft a PDF which leads to large memory usage. This requires parsing the content stream using the RunLengthDecode filter. This has been fixed in pypdf 6.7.4. As a workaround, consider applying the changes from PR #3664.

Vulnerability class: DoS (Denial of Service)

Published 2026-02-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.

EPSS exploit prediction

EPSS: 0.005 (42.9th percentile), scored 2026-09-29.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 43rd percentile — 42.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.005 · change: +0.001

Affected products

Py-Pdf Pypdf — versions < 6.7.4
Pypdf Project

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

References

github.com/py-pdf/pypdf/security/advisories/GHSA-f2v5-7jq9-h8cg (Patch, Vendor Advisory)
github.com/py-pdf/pypdf/pull/3664 (Patch, Issue Tracking)
github.com/py-pdf/pypdf/commit/f309c6003746414dc7b5048c19e6d879ff2dc858 (Patch)
github.com/py-pdf/pypdf/releases/tag/6.7.4 (Release Notes)

Frequently asked questions

What is CVE-2026-28351?: CVE-2026-28351 is a medium-severity vulnerability in Py-Pdf Pypdf, classified under Uncontrolled Resource Consumption. CVSS score: 5.3/10. Published 2026-02-27.
How severe is CVE-2026-28351?: Medium severity. CVSS v3 base score is 5.3 out of 10.