CVE-2026-33393

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Source
https://cve.org/CVERecord?id=CVE-2026-33393
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33393.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-33393
Aliases
Published
2026-03-19T22:04:26.484Z
Modified
2026-07-15T01:49:05.030200773Z
Severity
  • 4.3 (Medium) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N CVSS Calculator
Summary
Discourse fixes loose hostname matching in spam host allowlist
Details

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the allowed_spam_host_domains check used String#end_with? without domain boundary validation, allowing domains like attacker-example.com to bypass spam protection when example.com was allowlisted. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 require exact match or proper subdomain match (preceded by .) to prevent suffix-based bypass of newuser_spam_host_threshold. No known workarounds are available.

Database specific 
{
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33393.json",
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
        "CWE-284"
    ]
}
References

Affected packages

Git / github.com/discourse/discourse

Affected ranges

Type
GIT
Repo
https://github.com/discourse/discourse
Events
Introduced
322d3c0ac6a8f133b3f82875e9dbbe310f638c1b
Fixed
808b2ac23d8ff421563b40203091026732471c60
Introduced
f7cec86997edc21d6074ceb7666f7e2e6e1b1fdf
Fixed
f38464e46df1b8c51f7d60826502476908d6bb2b
Introduced
896e810e1b296478bba91559a8fc89a9926f11fe
Fixed
80b19c15fe9c7bc890d1a54f454c8446312ac6d2
Fixed
d8467b9fbb3d9ed6047b4e508d3fef88a37b8a02
Fixed
f99099cfbc6b76fe39d6fa2daa48efd69497fb8e
Database specific 
{
    "cpe": [
        "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*",
        "cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest:*:*:*"
    ],
    "extracted_events": [
        {
            "introduced": "2026.1.0"
        },
        {
            "fixed": "2026.1.2"
        },
        {
            "introduced": "2026.2.0"
        },
        {
            "fixed": "2026.2.1"
        },
        {
            "introduced": "2026.3.0"
        },
        {
            "last_affected": "2026.3.0"
        }
    ],
    "source": [
        "CPE_RANGE",
        "CPE_STRING",
        "REFERENCES"
    ]
}

Affected versions

2026.*
2026.3.0
= 2026.*
= 2026.3.0-latest
Other
esr
stable
v2026.*
v2026.1.0
v2026.1.0-latest
v2026.1.1
v2026.2.0
v2026.2.0-latest
v2026.3.0-latest

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33393.json"