CVE-2026-30975
Summary
Sonarr is a PVR for Usenet and BitTorrent users. Versions prior to 4.0.16.2942 have an authentication bypass that affected users that had disabled authentication for local addresses (Authentication Required set to: `Disabled for Local Addresses`) without a reverse proxy running in front of Sonarr that didn't not pass through the invalid header. Patches are available in version 4.0.16.2942 in the nightly/develop branch and version 4.0.16.2944 for stable/main releases. Some workarounds are available. Make sure Sonarr's Authentication Required setting is set to `Enabled`, run Sonarr behind a reverse proxy, and/or do not expose Sonarr directly to the internet and instead rely on accessing it through a VPN, Tailscale or a similar solution.
Impact & exploitability
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
Affected products we track (1)
Recommendation
Apply the vendor fix promptly. Open any affected product above for its exact safe version.