Security readout for executives and security teams
Plain-English summary
Mattermost Server versions before 4.3.0, 4.2.1, and 4.1.2 allowed someone who knew another user’s session ID to revoke that user’s session. The confirmed impact is forced logout or session disruption, not account takeover. Severity data and exploit evidence are not provided in the source bundle.
Executive priority
Handle as a targeted availability and trust issue for Mattermost users. Prioritize remediation if Mattermost is business-critical or session IDs may be exposed internally. The evidence does not support calling this critical or actively exploited.
Technical view
The CVE describes improper session revocation control in Mattermost Server before the fixed release lines. If an attacker obtains a session ID, they can revoke another user’s session. The sources do not provide CVSS, CWE, attack vector, privilege requirements, patch details, or proof of exploitation.
Likely exposure
Exposure is limited to Mattermost Server deployments running versions earlier than 4.3.0, 4.2.1, or 4.1.2. Risk is higher where session IDs may be exposed through logs, browser data, support artifacts, or shared operational tooling.
Exploitation context
The source bundle does not show CISA KEV listing, public exploitation, or exploit tooling. It only states the condition: knowledge of a session ID allows revoking another user’s session. Treat exploitation status as unconfirmed.
Researcher notes
The record is sparse: no CVSS, CWE, affected CPEs, exploit status, or detailed vendor advisory text is included. Analysis should stay anchored to the stated behavior and fixed-version boundaries until Mattermost provides more detail.
Mitigation direction
- Upgrade Mattermost Server to a fixed version for the deployed branch.
- Review Mattermost security updates for branch-specific guidance.
- Reduce unnecessary access to logs or artifacts containing session IDs.
- After remediation, consider invalidating exposed or suspicious sessions.
Validation and detection
- Inventory Mattermost Server versions across production and staging.
- Confirm no deployment is older than 4.3.0, 4.2.1, or 4.1.2.
- Check whether session IDs appear in logs, tickets, or support bundles.
- Review available logs for unusual session revocation patterns.
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-2017-18878 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.