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Neko has a Self-service Privilege Escalation for Authenticated Users

High severity GitHub Reviewed Published Apr 19, 2026 in m1k1o/neko • Updated Apr 21, 2026

Package

gomod github.com/m1k1o/neko/server (Go)

Affected versions

>= 3.0.0, < 3.0.11
>= 0.0.0-20250322225643-212bf8a60756, < 0.0.0-20260406184107-c54bcf1ee211

Patched versions

3.0.11
0.0.0-20260406184107-c54bcf1ee211

Description

Impact

Any authenticated user can immediately obtain full administrative control of the entire Neko instance (member management, room settings, broadcast control, session termination, etc.). This results in a complete compromise of the instance.

Patches

The vulnerability has been patched in the following releases:

Users should upgrade to v3.0.11 or later (for the 3.0 branch) or v3.1.2 or later.

Workarounds

If upgrading is not immediately possible, the following mitigations can reduce risk:

  • Restrict access to trusted users only (avoid granting accounts to untrusted parties)
  • Run the instance only when needed; avoid leaving it continuously exposed
  • Disable or restrict access to the /api/profile endpoint if feasible
  • Monitor for suspicious privilege changes or unexpected administrative actions

Note: These are temporary mitigations and do not fully eliminate the vulnerability. Upgrading is strongly recommended.

Credits

Neko thanks @blitzkrieg-patch for responsibly disclosing this vulnerability and reaching out directly. This contribution helped strengthen the project, and the whole community benefits from it.

References

@m1k1o m1k1o published to m1k1o/neko Apr 19, 2026
Published by the National Vulnerability Database Apr 21, 2026
Published to the GitHub Advisory Database Apr 21, 2026
Reviewed Apr 21, 2026
Last updated Apr 21, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(16th percentile)

Weaknesses

Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. Learn more on MITRE.

Improper Privilege Management

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Learn more on MITRE.

Improper Access Control

The product does not restrict or incorrectly restricts access to a resource from an unauthorized actor. Learn more on MITRE.

Authorization Bypass Through User-Controlled Key

The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. Learn more on MITRE.

Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.

CVE ID

CVE-2026-39386

GHSA ID

GHSA-2gw9-c2r2-f5qf

Source code

Credits

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