Security readout for executives and security teams
Plain-English summary
Mysterium Node versions from v1.21.1-rc0 before v1.36.0 can let an unauthenticated network attacker change node configuration and take over the node. This is critical because no login or user interaction is required, and the CVSS record rates confidentiality, integrity, and availability impact as high.
Executive priority
Treat this as urgent for any organization operating Mysterium Node. The business risk is complete node takeover without authentication if the management API is reachable. Prioritize upgrade and network restriction, then investigate whether configuration was changed unexpectedly.
Technical view
The issue is CWE-862 improper authorization in /tequilapi/config/user. The CVE states a crafted POST request can arbitrarily overwrite configuration and lead to full node takeover. Affected scope is Mysterium Node v1.21.1-rc0 through versions before v1.36.0. CVSS v3.1 is 9.8: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
Likely exposure
Exposure is likely where Mysterium Node runs an affected version and the Tequilapi configuration endpoint is reachable by untrusted networks. The bundle does not provide CPEs, deployment defaults, or internet-exposure measurements, so asset owners must verify actual endpoint reachability and version locally.
Exploitation context
The CVE is not listed as KEV in the provided bundle, so active exploitation is not established here. The bundle references a public CVE-specific GitHub repository and a vendor commit, indicating public technical visibility. The described attack requires network access to the affected endpoint, no credentials, and no user interaction.
Researcher notes
The source bundle gives a precise vulnerable endpoint, version range, CWE, CVSS vector, vendor commit, and CVE-specific repository reference. It does not provide CPEs, confirmed exploitation, deployment defaults, or detailed patch notes. Avoid assuming exposure unless Tequilapi reachability and affected versions are confirmed.
Mitigation direction
- Upgrade Mysterium Node to v1.36.0 or later if vendor guidance confirms that version remediates it.
- Restrict Tequilapi access to trusted management networks only.
- Block unauthenticated external access to /tequilapi/config/user.
- Review vendor repository and advisory sources for updated remediation guidance.
- Rotate credentials or sensitive node configuration if compromise is suspected.
Validation and detection
- Inventory all Mysterium Node instances and record exact versions.
- Confirm whether any instance is v1.21.1-rc0 or later but before v1.36.0.
- Check whether the Tequilapi service is reachable from untrusted networks.
- Review logs for unexpected configuration changes around /tequilapi/config/user.
- Verify upgraded nodes no longer expose the vulnerable behavior per vendor guidance.
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-862: 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-2026-31309 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
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
SSVC decision data
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:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/mysteriumnetwork/node/CVE reference, mitre
- https://github.com/mysteriumnetwork/node/commit/bc099fcaff59fee9c8a8f8e07ffff5b3c5df2bb9CVE reference, mitre
- https://github.com/sch8ill/CVE-2026-31309CVE reference, mitre
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.
Missing Authorization
Missing Authorization represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.