Vulnerability in Fontconfig Project

CVE-2026-34085

fontconfig before 2.17.1 has an off-by-one error in allocation during sfnt capability handling, leading to a one-byte out-of-bounds write, and potentially a crash or code execution. This is in FcFontCapabilities in fcfreetype.c.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.002 (7.0th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 7th percentile — 7.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-34085: held from 0.001 to 0.002.

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

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-34085?
CVE-2026-34085 is a medium-severity vulnerability in Fontconfig Project, classified under Off-by-one Error. CVSS score: 5.9/10. Published 2026-03-25.
How severe is CVE-2026-34085?
Medium severity. CVSS v3 base score is 5.9 out of 10.