What is CVE-2026-27888?

CVE-2026-27888 is a high-severity vulnerability in Py-Pdf Pypdf, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-02-26.

How severe is CVE-2026-27888?

High severity. CVSS v3 base score is 7.5 out of 10.

Resource exhaustion in Py-Pdf Pypdf

CVE-2026-27888

pypdf is a free and open-source pure-python PDF library. Prior to 6.7.3, an attacker who uses this vulnerability can craft a PDF which leads to the RAM being exhausted. This requires accessing the `xfa` property of a reader or writer and the corresponding stream being compressed using `/FlateDecode`. This has been fixed in pypdf 6.7.3. As a workaround, apply the patch manually.

Vulnerability class: DoS (Denial of Service)

Published 2026-02-26 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.003 (28.4th percentile), scored 2026-09-23.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 28.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: 0.000

Affected products

Py-Pdf Pypdf — versions < 6.7.3
Pypdf Project

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

References

github.com/py-pdf/pypdf/security/advisories/GHSA-x7hp-r3qg-r3cj (Patch, Vendor Advisory)
github.com/py-pdf/pypdf/pull/3658 (Patch, Issue Tracking)
github.com/py-pdf/pypdf/commit/7a4c8246ed48d9d328fb596942271da47b6d109c (Patch)
github.com/py-pdf/pypdf/releases/tag/6.7.3 (Product, Release Notes)

Frequently asked questions

What is CVE-2026-27888?: CVE-2026-27888 is a high-severity vulnerability in Py-Pdf Pypdf, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-02-26.
How severe is CVE-2026-27888?: High severity. CVSS v3 base score is 7.5 out of 10.