Security readout for executives and security teams
Plain-English summary
Older Matrix Synapse servers could let an unauthorised user take control of a room if that room had no active m.room.power_levels event. The issue is business-relevant where Matrix rooms carry operational or sensitive discussions, because control of a room affects trust, moderation, and access governance.
Executive priority
Treat as urgent for organisations using older Synapse deployments for trusted collaboration. Prioritise patch verification and room-control review over broad emergency response unless internal evidence shows suspicious room changes.
Technical view
CVE-2018-12423 affects Synapse before 0.31.2. The vulnerable condition is a Matrix room without an m.room.power_levels event in force, allowing unauthorised room hijacking. The public bundle does not provide CVSS, CWE, detailed exploit mechanics, or broad affected-version metadata beyond the pre-0.31.2 statement.
Likely exposure
Exposure is likely limited to Matrix Synapse homeservers running versions before 0.31.2, specifically rooms missing an effective m.room.power_levels event. The provided affected-product metadata is incomplete, so confirm actual Synapse deployment versions and room state directly.
Exploitation context
The bundle does not show CISA KEV listing or cite active exploitation. Public references describe a security update and related protocol discussion, but the supplied evidence does not establish real-world exploitation.
Researcher notes
The key research constraint is the missing power-level event condition. Public metadata lacks CVSS and detailed product enumeration, so analysis should stay focused on Synapse before 0.31.2 and affected room state rather than assuming wider Matrix ecosystem exposure.
Mitigation direction
- Upgrade Synapse to version 0.31.2 or later.
- Review the Matrix security update for vendor-specific guidance.
- Inventory rooms missing an effective m.room.power_levels event.
- Restore appropriate room power-level state where missing.
- Review room administrators and moderation privileges for unexpected changes.
Validation and detection
- Confirm all Synapse homeservers are running 0.31.2 or later.
- Check room state for missing m.room.power_levels events.
- Audit sensitive rooms for unexpected ownership or privilege changes.
- Review available logs for anomalous room-control changes.
- Document any rooms that could not be fully validated.
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-2018-12423 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://matrix.org/blog/2018/06/14/security-update-synapse-0-31-2/CVE reference · x_refsource_MISC
- https://github.com/matrix-org/matrix-doc/issues/1304CVE reference · x_refsource_MISC
- https://bugs.debian.org/901549CVE 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.