Kavita 0.9.0 through 0.9.1.4 SSRF Blocklist Bypass via upload-cbl-file Endpoint

Advisories

Kavita 0.9.0 through 0.9.1.4 SSRF Blocklist Bypass via upload-cbl-file Endpoint

severity: low
date: 10/13/2026
Affecting: Kavita >= 0.9.0, <= 0.9.1.4
CVE: CVE-2026-110223
CWE: CWE-918 Server-Side Request Forgery (SSRF)
CVSS: 2.3
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
References: https://hackmd.io/@1ExmmukzRMWN7B4gQ4W-4Q/kavita-cbl-url-preflight-ssrf
https://github.com/Kareadita/Kavita/blob/879b8b73eb41d66f88dde8eb874cc99a3397eb11/Kavita.Server/Controllers/CBLController.cs#L82-L108
https://github.com/Kareadita/Kavita/blob/879b8b73eb41d66f88dde8eb874cc99a3397eb11/Kavita.Common/Helpers/FlurlConfiguration.cs#L46-L89
https://github.com/Kareadita/Kavita
Credit: hieuPenguinnn
Description: Kavita 0.9.0 through 0.9.1.4 contains a server-side request forgery vulnerability that allows authenticated users to bypass the SSRF blocklist through DNS rebinding or HTTPS redirects. Attackers can submit a URL to POST /api/Cbl/upload-cbl-file whose host rebinds or redirects to internal addresses after validation, enabling blind internal port and service probing.

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