Discourse up to 2026.1.1/2026.2.0/2026.3.0-latest allowed_names information disclosure

CVSS Meta Temp Score
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CTI Interest Score
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4.2$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Discourse up to 2026.1.1/2026.2.0/2026.3.0-latest. This affects the function allowed_names. The manipulation leads to information disclosure. This vulnerability is documented as CVE-2026-31869. The attack can be initiated remotely. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Discourse up to 2026.1.1/2026.2.0/2026.3.0-latest. This issue affects the function allowed_names. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. The summary by CVE is:

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.

The advisory is shared at github.com. The identification of this vulnerability is CVE-2026-31869 since 03/09/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1592 for this issue.

Upgrading to version 2026.1.2 or 2026.2.1 eliminates this vulnerability.

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.3
NVD Vector: 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Information disclosure
CWE: CWE-200 / CWE-284 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Discourse 2026.1.2/2026.2.1

Timelineinfo

03/09/2026 CVE reserved
03/20/2026 +11 days Advisory disclosed
03/20/2026 +0 days VulDB entry created
03/25/2026 +5 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-5f9h-vp7v-7vq5
Status: Confirmed

CVE: CVE-2026-31869 (🔒)
GCVE (CVE): GCVE-0-2026-31869
GCVE (VulDB): GCVE-100-351821

Entryinfo

Created: 03/20/2026 07:23
Updated: 03/25/2026 14:34
Changes: 03/20/2026 07:23 (68), 03/25/2026 14:34 (11)
Complete: 🔍
Cache ID: 216::103

If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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