Security readout for executives and security teams
Plain-English summary
Canonical Multipass for Windows before 1.7.0 let any local process use a localhost control socket to mount host operating system paths into a guest. That could turn a low-privileged local foothold into broader access. This is not described as remotely exploitable, and the provided sources do not show active exploitation.
Executive priority
Treat this as high priority for Windows systems using Multipass, especially shared engineering infrastructure. It is a local privilege-escalation issue, so urgency depends on whether attackers or untrusted users can already run code on those hosts.
Technical view
The issue affects Windows Multipass before 1.7.0. An unauthenticated localhost TCP control socket allowed local processes to request mounts from host OS to guest, creating a privilege-escalation path. CVSS 3.1 is 8.8 with local attack vector, low complexity, low privileges required, no user interaction, changed scope, and high CIA impact.
Likely exposure
Exposure is most likely on Windows developer workstations, shared build hosts, or CI runners running Canonical Multipass before 1.7.0. Risk increases where untrusted local users, scripts, or compromised low-privilege processes can run on the host.
Exploitation context
The bundle marks CISA KEV as false, and no cited source states active exploitation. The attack requires local code execution or local user access on the Windows host; the provided evidence does not support internet-facing remote exploitation.
Researcher notes
Key weaknesses are CWE-284 and CWE-73. The authoritative description identifies an unauthenticated localhost TCP control socket and host-to-guest mount capability. The provided evidence is enough for affected-version triage, but not for claiming exploitation in the wild.
Mitigation direction
- Upgrade Windows Multipass installations to version 1.7.0 or later.
- Prioritize shared Windows hosts and developer endpoints running Multipass.
- Check Canonical Multipass guidance and release notes for any additional vendor recommendations.
- Restrict local access on affected hosts until upgraded.
- Review endpoint controls for untrusted local scripts or users.
Validation and detection
- Inventory Windows systems for Canonical Multipass installations.
- Identify any Multipass versions earlier than 1.7.0.
- Confirm upgraded hosts report Multipass 1.7.0 or later.
- Review shared workstations and CI runners for local untrusted-user exposure.
- Record remediation status for each affected Windows host.
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 lookupCWE-73: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. 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 lookupPrivilege behavior lookup
The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-3626 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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.
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:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H26Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/canonical/multipass/pull/2150CVE 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.
External Control of File Name or Path
External Control of File Name or Path represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.