What is the CVSS score of CVE-2026-39386?

CVE-2026-39386 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

Which versions of Neko are affected by CVE-2026-39386?

Neko self-hosted virtual browser versions 3.0.0-3.0.10 and 3.1.0-3.1.1 contain a privilege escalation vulnerability allowing authenticated users to gain full administrator control, enabling…. A patch is available.

How to fix or mitigate CVE-2026-39386?

Within 24 hours: Identify all Neko instances running versions 3.0.0-3.0.10 or 3.1.0-3.1.1 via asset inventory and restrict access to trusted personnel only. Within 7 days: Upgrade to vendor-released patch versions 3.0.11 or 3.1.2 respectively, with testing in non-production environment first. Within 30 days: Conduct access review of all administrative actions performed during the vulnerable period and audit member/room configuration changes for unauthorized modifications.

Neko CVE-2026-39386

EUVD-2026-24027 HIGH

Improper Input Validation (CWE-20)

2026-04-21 GitHub_M

GHSA-2gw9-c2r2-f5qf

Information Disclosure Docker

8.8

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

8.8 HIGH

AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Patch released

Apr 23, 2026 - 18:21 nvd

Patch available

Re-analysis Queued

Apr 21, 2026 - 16:22 vuln.today

cvss_changed

Patch available

Apr 21, 2026 - 02:01 EUVD

Analysis Generated

Apr 21, 2026 - 01:23 vuln.today

EUVD ID Assigned

Apr 21, 2026 - 01:15 euvd

EUVD-2026-24027

Analysis Generated

Apr 21, 2026 - 01:15 vuln.today

CVE Published

Apr 21, 2026 - 00:50 nvd

HIGH 8.8

DescriptionGitHub Advisory

Neko is a a self-hosted virtual browser that runs in Docker and uses WebRTC In versions 3.0.0 through 3.0.10 and 3.1.0 through 3.1.1, 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. The vulnerability has been patched in v3.0.11 and v3.1.2. If upgrading is not immediately possible, the following mitigations can reduce risk: Restrict access to trusted users only (avoid granting accounts to untrusted parties); ensure all user passwords are strong and only shared with trusted individuals; run the instance only when needed; avoid leaving it continuously exposed; place the instance behind authentication layers such as a reverse proxy with additional access controls; disable or restrict access to the /api/profile endpoint if feasible; and/or monitor for suspicious privilege changes or unexpected administrative actions. Note that these are temporary mitigations and do not fully eliminate the vulnerability. Upgrading is strongly recommended.

AnalysisAI

Privilege escalation in Neko virtual browser (versions 3.0.0-3.0.10, 3.1.0-3.1.1) allows any authenticated user with low privileges to immediately gain full administrative control over the entire instance, including member management, room settings, broadcast control, and session termination. This complete instance compromise requires only network access and valid user credentials (CVSS 8.8, AV:N/AC:L/PR:L). While EPSS exploitation probability is low (0.12%, 31st percentile) and no active exploitation has been confirmed, the vulnerability is trivially exploitable by any authenticated user and classified as non-automatable but with total technical impact per SSVC. Vendor patches are available in versions 3.0.11 and 3.1.2.

Technical ContextAI

Neko is a self-hosted virtual browser application running in Docker containers that uses WebRTC for streaming. The vulnerability stems from improper input validation (CWE-20) affecting the /api/profile endpoint. Based on CPE data (cpe:2.3:a:m1k1o:neko), this affects the m1k1o Neko project specifically. The flaw allows authenticated users to manipulate API calls to elevate their privileges from standard user to full administrator without additional authorization checks. This represents a broken access control issue where authentication alone is insufficient to enforce role-based restrictions, allowing horizontal privilege escalation through the profile management interface. The Docker deployment model means compromised instances could potentially affect containerized environments depending on configuration.

RemediationAI

Apply vendor-released patches immediately: upgrade to Neko v3.0.11 for the 3.0.x branch (https://github.com/m1k1o/neko/releases/tag/v3.0.11) or v3.1.2 for the 3.1.x branch (https://github.com/m1k1o/neko/releases/tag/v3.1.2). If immediate patching is not feasible, implement layered compensating controls: restrict instance access exclusively to trusted administrators and avoid creating accounts for untrusted users (reduces attack surface but does not eliminate insider risk); enforce strong password policies and credential rotation for all existing accounts; shut down the instance when not actively needed rather than maintaining continuous availability (limits exposure window); deploy a reverse proxy with additional authentication layers such as OAuth, SAML, or mutual TLS in front of the Neko instance (adds defense-in-depth but introduces latency and management overhead); block or restrict access to the /api/profile endpoint at the reverse proxy or firewall level if application functionality permits (may break profile management features); implement real-time monitoring for privilege escalation events and administrative action anomalies using container logs and SIEM correlation. Note that all compensating controls are temporary risk reduction measures and do not eliminate the underlying vulnerability-upgrading remains the only complete fix.