dbcve.org
NekoApplication · M1k1o

CVE-2026-39386

HIGH · 8.8 CVSS v3.1 Published 2026-04-21
Fix available
A fix is available. Upgrade to 3.0.11 / 3.1.2 or later.
See remediation →
94/100
Remediation priority · Urgent
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Neko virtual browser versions 3.0.0-3.0.10 and 3.1.0-3.1.1, any authenticated user can escalate privileges to full administrative control, enabling member management, room settings, broadcast control, and session termination—resulting in complete instance compromise.

MitigationUpgrade to Neko v3.0.11 or v3.1.2 which contains the security patch; alternatively, restrict access to trusted users, enforce strong passwords, and consider additional authentication layers as temporary mitigations until upgrading is possible.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
NekoApplication
Affected:>= 3.0.0, < 3.0.11>= 3.1.0, < 3.1.2

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Neko installation
    Locate the Neko browser instance by checking running services, Docker containers, or installed packages named 'neko' or looking for the web interface typically on ports 8080 or 80.
    Affected if Neko browser is installed and running on the system
  2. Determine installed Neko version
    Check the version of the installed Neko instance by inspecting the Docker image tag, package version, or accessing the /about/version endpoint if available in the web interface.
    Affected if The version is 3.0.0 through 3.0.10, or 3.1.0 through 3.1.1 (falls within the affected ranges)
  3. Verify authentication is enabled
    Inspect the Neko configuration file or environment variables to confirm that user authentication is configured and enabled (look for NEKO_USERNAME, NEKO_PASSWORD, or auth-related settings).
    Affected if Authentication is enabled, meaning untrusted users can authenticate to the instance
  4. Check for existing user accounts
    Review the user management settings or database to identify all accounts that have access to the Neko instance, particularly any non-admin or low-privilege users.
    Affected if There are multiple authenticated users or any user other than the primary administrator

If Neko is running and the version falls within 3.0.0-3.0.10 or 3.1.0-3.1.1 with authentication enabled and multiple users exist, the environment is vulnerable to full administrative compromise.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 3.0.11 / 3.1.2 or later
Fixed in 3.0.113.1.2
Interim mitigation

Upgrade to Neko v3.0.11 or v3.1.2 which contains the security patch; alternatively, restrict access to trusted users, enforce strong passwords, and consider additional authentication layers as temporary mitigations until upgrading is possible.

Recommended fix High confidence

Upgrade to Neko v3.0.11 or v3.1.2 (choose the appropriate branch based on your current version)

  1. Backup the current Neko configuration and any persistent data
  2. Pull the fixed Neko Docker image (v3.0.11 for 3.0.x branch or v3.1.2 for 3.1.x branch)
  3. Stop the existing Neko container
  4. Recreate the container using the new image with the same configuration
  5. Verify the container starts successfully
  6. Test that authentication works and that regular users cannot escalate privileges to admin
  7. Confirm the /api/profile endpoint behavior has been corrected

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Neko Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-39386 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data