What is CVE-2026-72583?

CVE-2026-72583 is a medium-severity vulnerability in Fastschema, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-08-10.

How severe is CVE-2026-72583?

Medium severity. CVSS v3 base score is 5.4 out of 10.

XSS in Fastschema

CVE-2026-72583

A stored cross-site scripting (XSS) vulnerability in fastschema through v0.15.1 allows a low-privileged authenticated user to upload an SVG file containing malicious JavaScript by bypassing the MIME type allow-list check.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-08-10 · last modified 2026-08-28.

CVSS v3 metric

CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.002 (4.6th percentile), scored 2026-09-24.

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: 0.002 · newest: 0.002 · change: 0.000

Affected products

Fastschema — versions 0

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c (third-party-advisory)
309f9ea4-e3e9-4c6c-b79d-e8eb01244f2c (technical-description)

Frequently asked questions

What is CVE-2026-72583?: CVE-2026-72583 is a medium-severity vulnerability in Fastschema, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2026-08-10.
How severe is CVE-2026-72583?: Medium severity. CVSS v3 base score is 5.4 out of 10.