HOMEVULNERABILITIESCVE-2026-33393
MEDIUM

CVE-2026-33393

CWE-284Published: March 19, 2026· Updated: Mar 24, 2026

4.3
CVSS v3.1
EPSS:0.03%probability of exploitation in 30 daysPercentile:7.2th

Official Description

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.

NVD Source

Technical Analysis

CVE-2026-33393 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.Low
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected Vendors & Products

discourse1 product
discourse
Source: NVD CPE · 2 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

PATCHhttps://github.com/discourse/discourse/commit/80b19c15fe9c7bc890d1a54f454c8446312ac6d2
PATCHhttps://github.com/discourse/discourse/commit/d8467b9fbb3d9ed6047b4e508d3fef88a37b8a02
PATCHhttps://github.com/discourse/discourse/commit/f99099cfbc6b76fe39d6fa2daa48efd69497fb8e
ADVISORYhttps://github.com/discourse/discourse/security/advisories/GHSA-95r5-p6qr-hgw6

All References (4)

→
https://github.com/discourse/discourse/commit/80b19c15fe9c7bc890d1a54f454c8446312ac6d2Patch
→
https://github.com/discourse/discourse/commit/d8467b9fbb3d9ed6047b4e508d3fef88a37b8a02Patch
→
https://github.com/discourse/discourse/commit/f99099cfbc6b76fe39d6fa2daa48efd69497fb8ePatch
→
https://github.com/discourse/discourse/security/advisories/GHSA-95r5-p6qr-hgw6Vendor Advisory

Quick Facts

CVE IDCVE-2026-33393
CVSS Score4.3 / 10
SeverityMEDIUM
WeaknessCWE-284
CISA KEVNo
EPSS (30d)0.03%
Affected1 vendor
PublishedMar 19, 2026

Related CVEs (CWE-284)

CVE-2026-35308
10.0
CVE-2026-46978
10.0
CVE-2026-48907
KEV10.0
CVE-2026-46695
10.0
CVE-2026-48908
KEV10.0
CVE-2026-35435
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2026-33393 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.
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