What is CVE-2026-37503?

CVE-2026-37503 is a medium-severity vulnerability in V2board, classified under Cross-site Scripting. CVSS score: 6.9/10. Published 2026-05-01.

How severe is CVE-2026-37503?

Medium severity. CVSS v3 base score is 6.9 out of 10.

XSS in V2board

CVE-2026-37503

Cross-Site Scripting (XSS) in V2Board thru 1.7.4. The custom_html field in theme configuration is rendered using Blade unescaped output in public/theme/v2board/dashboard.blade.php. An admin can inject arbitrary JavaScript via the saveThemeConfig API. All site visitors execute the payload, enabling cookie theft, session hijacking, or phishing.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2026-05-01 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.9 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.003 (19.4th percentile), scored 2026-10-06.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 19th percentile — 19.4% 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: 0.003 · change: +0.001

Affected products

V2board

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

References

github.com/v2board/v2board (Product)
gist.github.com/sgInnora/1330e1a82caa79906eec55eeff2c99b9 (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2026-37503?: CVE-2026-37503 is a medium-severity vulnerability in V2board, classified under Cross-site Scripting. CVSS score: 6.9/10. Published 2026-05-01.
How severe is CVE-2026-37503?: Medium severity. CVSS v3 base score is 6.9 out of 10.