CVE-2026-727215.3MediumCWE-178

CVE-2026-72721: Discourse: Onebox Domain Blocklist Bypass via Case-Sensitive Comparison

discourse

Affected: discourse · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.6%probability of exploitation in the next 30 days

48th percentile

050100

Higher than 48% of scored CVEs

5.3MediumCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

discourse · discourse< 2026.1.6; >= 2026.5.0-latest, < 2026.5.2; >= 2026.6.0-latest, < 2026.6.1; >= 2026.7.0-latest, < 2026.7.0

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Improper Handling of Case Sensitivity · Input Validation and Logic
Vendor: discourse
Published: August 2026
Band: Unlikely (under 1%), August 2026

CoverageNo articles yet

No CyberSIXT article names CVE-2026-72721 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.