Is CVE-2026-31869 in the CISA KEV catalog?

No. CVE-2026-31869 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-31869?

CVE-2026-31869 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2026-31869?

CVE-2026-31869 has an EPSS score of 0.18% (8th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-31869?

Upgrade discourse to 2026.2.1 or later.

CVE & CISA-KEV Catalog

CVE-2026-31869

MEDIUM

4.3

CVSS v3

NVD

Description

Discourse is an open-source discussion platform. Prior to versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2, the ComposerController#mentions endpoint reveals hidden group membership to any authenticated user who can message the group. By supplying allowed_names referencing a hidden-membership group and probing arbitrary usernames, an attacker can infer membership based on whether user_reasons returns "private" for a given user. This bypasses group member-visibility controls. Versions 2026.3.0-latest.1, 2026.2.1, and 2026.1.2 contain a patch. To work around this issue, restrict the messageable policy of any hidden-membership group to staff or group members only, so untrusted users cannot reach the vulnerable code path.

CWE-200Information Exposure CWE-285 CWE-639Authorization Bypass Through User-Controlled Key

How to fix

Remediation Available

discourseNVD

Affected:>= 2026.2.0, < 2026.2.1Fixed in:2026.2.1CVE-2026-31869derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Exploit Intelligence

0.18%probability of exploitation in 30 days

8thpercentile

Low risk: more likely to be exploited than 8% of all known CVEs.

References

Vendor Advisory1

github.com

Related Vulnerabilities

Other CWE-200 (Information Exposure) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2024-24919	High	8.6	100%	KEV + Ransom	-
CVE-2020-14181	Medium	5.3	100%	-	Fix
CVE-2021-34429	Medium	5.3	99%	-	Fix
CVE-2018-11409	Medium	5.3	98%	-	-
CVE-2021-41277	Critical	10.0	97%	KEV	-
CVE-2016-2183	High	7.5	96%	-	Fix

Embed a live status badge for CVE-2026-31869

Markdown

[![CVE-2026-31869](https://tridentstack.com/cve/badge/CVE-2026-31869.svg)](https://tridentstack.com/cve/CVE-2026-31869)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-31869"><img src="https://tridentstack.com/cve/badge/CVE-2026-31869.svg" alt="CVE-2026-31869"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-03-24.