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High

Privilege Escalation via Unrestricted Localhost TCP Control Socket in Multipass for Windows

IdentifiersCVE-2021-3626CWE-269

In Multipass for Windows versions prior to 1.7.0, the application exposed a TCP control socket on localhost without proper access controls. This allowed any local process to connect to the socket and issue commands, including mounting arbitrary directories from the host OS into a guest VM. This flaw could be exploited by a local attacker to perform unauthorized actions, leading to privilege escalation.

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For your environment

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

A local attacker could exploit this vulnerability to gain elevated privileges by mounting sensitive host directories into a guest VM, potentially accessing or modifying files that should be restricted. This could lead to full compromise of the host system depending on the directories mounted and the privileges of the Multipass process.

Mitigation

If you can’t patch tonight, do this now.

As an interim mitigation, restrict local user access to the Multipass control socket and ensure that only trusted users have local access to the system. Network-level controls are not effective as the socket is bound to localhost, but local user privilege separation and monitoring may reduce risk until the software is updated.

Remediation

Patch, then assume compromise.

Upgrade Multipass for Windows to version 1.7.0 or later, where access controls on the TCP control socket have been properly implemented to restrict connections to authorized processes only.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
CanonicalMultipassapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence5

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity

Community discussion across Reddit, Mastodon, and other social sources.