Security readout for executives and security teams
Plain-English summary
Mattermost Server versions before 5.1 contain a denial-of-service issue tied to the invite_people slash command. An attacker could disrupt availability, but the source bundle does not provide CVSS scoring, detailed prerequisites, or confirmed active exploitation.
Executive priority
Treat this as an availability risk for legacy Mattermost deployments. Prioritize confirmation and upgrade for externally reachable or business-critical instances, while noting evidence is too sparse for a higher-confidence urgency rating.
Technical view
CVE-2018-21258 affects Mattermost Server before 5.1 and allows denial of service through the invite_people slash command. Public data here does not include CWE mapping, CVSS metrics, exploit maturity, authentication requirements, or detailed vendor remediation beyond the version boundary.
Likely exposure
Organizations running Mattermost Server versions older than 5.1 are the relevant exposure group. Exposure is higher where Mattermost is internet-accessible or supports critical collaboration workflows.
Exploitation context
CISA KEV is false in the provided bundle, and no cited source confirms active exploitation. The available description only states denial of service via a slash command.
Researcher notes
The public record is sparse: no CVSS vector, CWE, detailed affected CPEs, exploit status, or root-cause detail is provided. Analysis should stay anchored to Mattermost Server before 5.1 and denial-of-service impact.
Mitigation direction
- Inventory Mattermost Server instances and identify any versions before 5.1.
- Review Mattermost security updates and vendor upgrade guidance before remediation.
- Upgrade affected instances to 5.1 or a supported fixed release.
- Restrict Mattermost access where feasible until remediation is complete.
- Monitor service health for suspicious slash command-related disruption.
Validation and detection
- Confirm deployed Mattermost Server versions are 5.1 or later.
- Check asset records for retired or shadow Mattermost instances.
- Review logs for repeated invite_people slash command use near outages.
- Verify normal service availability after remediation.
- Document any compensating controls for systems not yet upgraded.
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.
CVE-2018-21258 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
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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 and timeline data
No CVSS vectors or timeline events were available in the normalized CVE source material.
Source materials
- CVE List V5 sourceCVE List V5
- https://mattermost.com/security-updates/CVE reference · x_refsource_CONFIRM
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.