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CVE-2026-72721

Discourse: Onebox Domain Blocklist Bypass via Case-Sensitive Comparison PUBLISHED

Description (CNA)

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 (CNA)

Vendor / productVersions
discourse / discourseaffected < 2026.1.6; affected >= 2026.5.0-latest, < 2026.5.2; affected >= 2026.6.0-latest, < 2026.6.1; affected >= 2026.7.0-latest, < 2026.7.0

CWE

CWE-178

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.