Improper input validation in Discourse

CVE-2026-72728

Discourse is an open-source discussion platform. Prior to 2026.1.7, an authenticated user could submit specially formed URLs that bypassed the Onebox allowlist and embedded malicious content in a site. This issue is fixed in versions 2026.1.7, 2026.6.2, 2026.7.1, and 2026.8.0-latest.1.

Vulnerability class: Drupalgeddon 2 (CVE-2018-7600)

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.003 (21.5th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 22nd percentile — 21.5% 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-2026-72728: held from 0.002 to 0.003.

EPSS over last 30 days · oldest: 0.002 · newest: 0.003 · change: +0.001

Affected products

  • Discourse — versions < 2026.1.7, >= 2026.6.0-latest, < 2026.6.2, >= 2026.7.0-latest, < 2026.7.1

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-72728?
CVE-2026-72728 is a medium-severity vulnerability in Discourse, classified under Improper Input Validation. CVSS score: 6.3/10. Published 2026-08-10.
How severe is CVE-2026-72728?
Medium severity. CVSS v3 base score is 6.3 out of 10.