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    CVE-2026-72721

    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.

    Published:Aug 10, 2026
    Last Modified:Aug 11, 2026
    EPS:Aug 10, 2026
    EPSS Score:
    CVSS Score:5.3

    Affected Products

    Vendor
    Discourse
    Product
    Discourse

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

    CVE-2026-53960 (CVSS 5.3) — Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, hidden o…
    CVE-2026-55704 (CVSS 4.3) — Discourse is an open-source discussion platform. Prior o 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, users who…
    CVE-2026-55674 (CVSS 9.3) — Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, an unaut…
    CVE-2026-59829 (CVSS 4.3) — Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.1, on sites…
    CVE-2026-72732 (CVSS 4.3) — Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, the disc…
    CVE-2026-72731 (CVSS 7.1) — Discourse is an open-source discussion platform. From 2026.1.0-latest until 2026.1.7, 2026.6.2, 2026.7.1, and …
    CVE-2026-72730 (CVSS 8.7) — Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, the Rich…
    CVE-2026-72729 (CVSS 2) — Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, the disc…
    CVE-2026-72728 (CVSS 6.3) — Discourse is an open-source discussion platform. Prior to 2026.1.7, an authenticated user could submit special…
    CVE-2026-72727 (CVSS 4.8) — Discourse is an open-source discussion platform. Prior to 026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, a low-pri…

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High