CVE-2026-27806: Github.com/fleetdm/fleet/v4 Fleet Affected By Local Privilege Vulnerability

HIGH
Advisory Identifier: GHSA-rphv-h674-5hp2
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CVSS 7.8
CWE-78
Published
Advisory Summary

CVE-2026-27806 is a HIGH (CVSS 7.8) fleet affected by local privilege vulnerability (CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')) affecting Github.com/fleetdm/fleet/v4 libraries in the Go ecosystem. The issue involves fleet affected by local privilege escalation via tcl command injection in orbit. Remediation is available by upgrading affected packages to version 4.81.1.

CVE-2026-27806 at a Glance

CVE Identifier CVE-2026-27806
GHSA Identifier GHSA-rphv-h674-5hp2
Severity HIGH
CVSS v3.1 Base Score 7.8
CWE Classification CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
Affected Product Github.com/fleetdm/fleet/v4
Package Ecosystem Go
Published Date
Last Updated

Security Impact

CVSS: 7.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Local (AV:L)
Attack Complexity Low (AC:L)
Privileges Required Low (PR:L)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2026-27806

To remediate this vulnerability, upgrade all affected Github.com/fleetdm/fleet/v4 dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/fleetdm/fleet/v4 fixed: 4.81.1 
Upgrade github.com/fleetdm/fleet/v4 to 4.81.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/fleetdm/fleet/v4

How to Check if You Are Affected

To determine whether your application is affected by CVE-2026-27806, inspect your project dependencies for Github.com/fleetdm/fleet/v4:

inspect dependencies for github.com/fleetdm/fleet/v4

Analyze the terminal output to locate any version of Github.com/fleetdm/fleet/v4 in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 4.81.1), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection'), where the product constructs all or part of an os command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended os command when it is sent to a downstream component. In Github.com/fleetdm/fleet/v4, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## Summary The Orbit agent's FileVault disk encryption key rotation flow on collects a local user's password via a GUI dialog and interpolates it directly into a Tcl/expect script executed via `exec.Command("expect", "-c", script)`. Because the password is inserted into Tcl brace-quoted `send {%s}`, a password containing `}` terminates the literal and injects arbitrary Tcl commands. Since Orbit runs as root, this allows a local unprivileged user to escalate to root privileges. ## CWE - **CWE-78**: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') - **CWE-94**: Improper Control of Generation of Code ('Code Injection') ## Impact - Local privilege escalation to root: Any unprivileged local user on a managed endpoint can execute arbitrary commands as root ## Credit This vulnerability was discovered and reported by [bugbunny.ai](https://bugbunny.ai).

CVE-2026-27806 Affected Github.com/fleetdm/fleet/v4 Versions

1 component(s)
Fixed Versions:
4.81.1
Product / Package Ecosystem Affected Versions Fixed Version
github.com/fleetdm/fleet/v4
golang/github.com/fleetdm/fleet/v4
Go
< 4.81.1
4.81.1

References

GitHub Advisory / Wiki ADVISORY
https://github.com/fleetdm/fleet/security/advisories/GHSA-rphv-h674-5hp2
Github.com/fleetdm/fleet/v4 Source Repository REPOSITORY
https://github.com/fleetdm/fleet

Frequently Asked Questions

What is CVE-2026-27806?
CVE-2026-27806 is a security vulnerability in Github.com/fleetdm/fleet/v4 involving Fleet Affected by Local Privilege Escalation via Tcl Command Injection in Orbit under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection').
Which Github.com/fleetdm/fleet/v4 versions are affected?
Affected versions include releases prior to 4.81.1 across affected packages: github.com/fleetdm/fleet/v4.
What version fixes CVE-2026-27806?
Upgrading to 4.81.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/fleetdm/fleet/v4 affected?
Yes, github.com/fleetdm/fleet/v4 is affected in releases prior to 4.81.1. Upgrade your dependency to 4.81.1 or later.
What is the CVSS score of CVE-2026-27806?
CVE-2026-27806 has a CVSS v3.1 base score of 7.8 (HIGH) with vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2026-27806?
CVE-2026-27806 is classified under CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection') (The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.).
How can I check Go dependencies for CVE-2026-27806?
Run the dependency tree command: 'inspect dependencies for github.com/fleetdm/fleet/v4'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rphv-h674-5hp2",
  "modified" : "2026-06-26T20:20:10Z",
  "published" : "2026-04-08T18:03:52Z",
  "aliases" : [ "CVE-2026-27806" ],
  "summary" : "Fleet Affected by Local Privilege Escalation via Tcl Command Injection in Orbit",
  "details" : "## Summary\n\nThe Orbit agent's FileVault disk encryption key rotation flow on collects a local user's password via a GUI dialog and interpolates it directly into a Tcl/expect script executed via `exec.Command(\"expect\", \"-c\", script)`. Because the password is inserted into Tcl brace-quoted `send {%s}`, a password containing `}` terminates the literal and injects arbitrary Tcl commands. Since Orbit runs as root, this allows a local unprivileged user to escalate to root privileges.\n\n## CWE\n\n- **CWE-78**: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')\n- **CWE-94**: Improper Control of Generation of Code ('Code Injection')\n\n## Impact\n\n- Local privilege escalation to root: Any unprivileged local user on a managed endpoint can execute arbitrary commands as root\n\n## Credit\n\nThis vulnerability was discovered and reported by [bugbunny.ai](https://bugbunny.ai).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/fleetdm/fleet/v4"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "4.81.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/fleetdm/fleet/security/advisories/GHSA-rphv-h674-5hp2"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/fleetdm/fleet"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-78" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-08T18:03:52Z",
    "nvd_published_at" : "2026-04-08T19:25:13Z"
  }
}