What is CVE-2026-42308?

CVE-2026-42308 is a medium-severity vulnerability in Python Pillow, classified under Integer Overflow or Wraparound. CVSS score: 5.5/10. Published 2026-05-09.

How severe is CVE-2026-42308?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Integer overflow in Python Pillow

CVE-2026-42308

Pillow is a Python imaging library. Prior to version 12.2.0, if a font advances for each glyph by an exceeding large amount, when Pillow keeps track of the current position, it may lead to an integer overflow. This issue has been patched in version 12.2.0.

Vulnerability class: Integer Overflow

Published 2026-05-09 · last modified 2026-07-24.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.002 (4.6th percentile), scored 2026-10-19.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 5th percentile — 4.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.001 · newest: 0.002 · change: +0.000

Affected products

Python Pillow
Python-Pillow Pillow — versions < 12.2.0

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

References

github.com/python-pillow/Pillow/security/advisories/GHSA-wjx4-4jcj-g98j (Vendor Advisory)
github.com/python-pillow/Pillow/releases/tag/12.2.0 (Product, Release Notes)

Frequently asked questions

What is CVE-2026-42308?: CVE-2026-42308 is a medium-severity vulnerability in Python Pillow, classified under Integer Overflow or Wraparound. CVSS score: 5.5/10. Published 2026-05-09.
How severe is CVE-2026-42308?: Medium severity. CVSS v3 base score is 5.5 out of 10.