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.
CVE-2026-33393
MEDIUMPre-NVD 4.34.3Trending — 3 sources updated this week
EchelonGraph scoreLOW confidence
This medium-severity CVE scores 4.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: secondary
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 4.3
- EG Score
- 4.3(low)
- EG Risk
- 24(Track)EG Risk 24/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity43% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- 0%
- EPSS %ILE
- 17%
- KEV
- Not listed
Published
March 19, 2026
Last Modified
June 17, 2026
References (4)
- security-advisories@githubhttps://github.com/discourse/discourse/commit/80b19c15fe9c7bc890d1a54f454c8446312ac6d2
- security-advisories@githubhttps://github.com/discourse/discourse/commit/d8467b9fbb3d9ed6047b4e508d3fef88a37b8a02
- security-advisories@githubhttps://github.com/discourse/discourse/commit/f99099cfbc6b76fe39d6fa2daa48efd69497fb8e
- security-advisories@githubhttps://github.com/discourse/discourse/security/advisories/GHSA-95r5-p6qr-hgw6
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 4× in last 7d / 4× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-30 16:28 UTCEPSS rescore
- 2026-07-30 01:30 UTCEPSS rescore
- 2026-07-27 14:38 UTCEG score recompute
- 2026-07-27 14:27 UTCOSV refresh
Frequently asked(5)
What is CVE-2026-33393?
CVE-2026-33393 is a medium vulnerability published on March 19, 2026. Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the allowedspamhostdomains check used String#endwith? without domain boundary validation, allowing domains like attacker-example.com to bypass spam protection when example.com was…
When was CVE-2026-33393 disclosed?
CVE-2026-33393 was first published in the National Vulnerability Database on March 19, 2026, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33393 actively exploited?
CVE-2026-33393 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 83.4% of all scored CVEs.
What is the CVSS score of CVE-2026-33393?
CVE-2026-33393 has a CVSS v3 base score of 4.3 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-33393?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33393, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-33393
Is Your Infrastructure Affected by CVE-2026-33393?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.