Security readout for executives and security teams
Plain-English summary
This is a low-severity Mattermost access-control issue. An authenticated user could see archived channel content that administrators intended to block. The business impact is limited to confidentiality of archived discussions, but it matters if those channels contain sensitive customer, legal, incident, or internal security information.
Executive priority
Handle during the next routine security maintenance cycle unless archived Mattermost channels contain sensitive regulated, customer, legal, or incident-response material. Escalate priority if older Mattermost versions remain internet-facing or broadly accessible to contractors or partners.
Technical view
Mattermost 6.1 and earlier insufficiently validated permissions for archived channel viewing. The CVE describes authenticated users viewing archived channel contents despite explicit administrative denial, by directly accessing APIs. CVSS 3.1 is 2.6 with low confidentiality impact and no integrity or availability impact.
Likely exposure
Exposure is limited to organizations running Mattermost 6.1 or earlier with archived channels containing restricted content. The attacker must already be authenticated, and the issue does not imply unauthenticated access or system compromise.
Exploitation context
The source bundle does not show CISA KEV listing or other evidence of active exploitation. The described path requires an authenticated user and specific archived-channel permission conditions. No public exploit status is provided in the sources.
Researcher notes
Track this as CWE-284 improper access control. The source bundle names Mattermost 6.1 and earlier, but does not provide detailed fixed-version mapping or exploit evidence. Validation should focus on version exposure, archived-channel confidentiality, and whether API access respects administrative denials.
Mitigation direction
- Identify Mattermost deployments running version 6.1 or earlier.
- Check Mattermost security updates for the fixed or vendor-recommended release.
- Upgrade or apply vendor guidance once the applicable fixed version is confirmed.
- Review archived channels for sensitive content and unnecessary membership.
- Restrict accounts and integrations that can access Mattermost APIs.
Validation and detection
- Inventory Mattermost versions across production, staging, and self-hosted instances.
- Review administrative settings for archived channel visibility and explicit access denials.
- Confirm archived channels containing sensitive data are still required.
- Use approved test accounts to verify denied users cannot view archived channel contents.
- Review logs for unusual archived-channel API access by authenticated users.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-284: Authorization and privilege behavior lookup
Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-37864 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Low
- CVSS
- 2.6 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N1.21.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
2.6LowVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:N/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://mattermost.com/security-updates/CVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Access Control
Improper Access Control represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.