Sonarr 4.0.9.2244/4.0.15.2940 authentication spoofing

Summaryinfo

A vulnerability described as critical has been identified in Sonarr. Impacted is an unknown function. Executing a manipulation can lead to authentication spoofing. This vulnerability is tracked as CVE-2026-30975. The attack can be launched remotely. No exploit exists. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as critical was found in Sonarr. This vulnerability affects an unknown code block. The manipulation with an unknown input leads to a authentication spoofing vulnerability. The CWE definition for the vulnerability is CWE-290. This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-30975 since 03/07/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available.

Upgrading to version 4.0.16.2942 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-15990). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

• Sonarr

Version

• 4.0.9.2244
• 4.0.15.2940

Website

• Product: https://github.com/Sonarr/Sonarr/

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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