Authentication bypass via spoofed forwarded address
Published Mar 25, 2026 · Updated Mar 25, 2026
Authentication bypass in Sonarr before 4.0.16.2942 allows remote attackers to access protected functions via a spoofed client IP. The authentication pipeline trusts an attacker-controlled X-Forwarded-For value when deciding whether a request originates from a local address. Exposure requires Authentication Required to be set to Disabled for Local Addresses and no correctly configured reverse proxy; successful requests can read and modify Sonarr data but do not interrupt the service.
Summary
What happened
Authentication bypass in Sonarr before 4.0.16.2942 allows remote attackers to access protected functions via a spoofed client IP. The authentication pipeline trusts an attacker-controlled X-Forwarded-For value when deciding whether a request originates from a local address. Exposure requires Authentication Required to be set to Disabled for Local Addresses and no correctly configured reverse proxy; successful requests can read and modify Sonarr data but do not interrupt the service.
The record
- CVE
- CVE-2026-30975
- Published
- Mar 25, 2026
- Updated
- Mar 25, 2026
- Vendor
- Sonarr
- Product
- Sonarr
- Classifications
- CWE-290, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 25, 2026CVE publishedPublication date reported by the CVE source.
- Mar 25, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 4.0.16.2942
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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