Neko has a Self-service Privilege Escalation for Authenticated Users

HIGH 8.8CVE-2026-39386 · GHSA-2gw9-c2r2-f5qf · GO-2026-4960 · Published 21/04/2026 · updated 26/10/2026

In short

CVE-2026-39386 is a HIGH (CVSS 8.8) vulnerability affecting github.com/m1k1o/neko/server, neko (m1k1o).
Chance of exploitation in the next 30 days (EPSS): 0.44%, higher than 38.2% of all vulnerabilities.
Fix: update to 0.0.0-20260406184107-c54bcf1ee211, 3.0.11, 3.1.2 or later.

Package	Affected versions	Patched versions
github.com/m1k1o/neko/server Go	`≥ 0.0.0-20250322225643-212bf8a60756, < 0.0.0-20260406184107-c54bcf1ee211≥ 0.0.0-20250326225119-51bbad7650d3, < 0.0.0-20260406184107-c54bcf1ee211≥ 3.0.0, < 3.0.11`	`0.0.0-20260406184107-c54bcf1ee2113.0.11`
neko m1k1o	`≥ 3.0.0, < 3.0.11≥ 3.1.0, < 3.1.2`	`3.0.113.1.2`

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:

v3.0.11 (backport release)
v3.1.2 (latest stable release)

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.

NVD description

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.

References

m1k1o/neko security advisory · WEB
nvd.nist.gov/vuln/detail/CVE-2026-39386 · ADVISORY
m1k1o/neko commit 6b561fe · WEB
m1k1o/neko commit c54bcf1 · WEB
m1k1o/neko · PACKAGE
m1k1o/neko release v3.0.11 · WEB
m1k1o/neko release v3.1.2 · WEB

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Package

Affected versions

Patched versions

github.com/m1k1o/neko/server

≥ 0.0.0-20250322225643-212bf8a60756, < 0.0.0-20260406184107-c54bcf1ee211≥ 0.0.0-20250326225119-51bbad7650d3, < 0.0.0-20260406184107-c54bcf1ee211≥ 3.0.0, < 3.0.11

0.0.0-20260406184107-c54bcf1ee2113.0.11

neko

m1k1o

≥ 3.0.0, < 3.0.11≥ 3.1.0, < 3.1.2

3.0.113.1.2

Description

Impact

Patches

The vulnerability has been patched in the following releases:

v3.0.11 (backport release)
v3.1.2 (latest stable release)

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.

NVD description