Blossom through 1.17.1 Authorization Bypass via Picture Delete and Star Endpoints

Advisories

Blossom through 1.17.1 Authorization Bypass via Picture Delete and Star Endpoints

Severity: medium
Date: 10/30/2026
Affecting: Blossom <= 1.17.1
CVE: CVE-2026-119644
CWE: CWE-639 Authorization Bypass Through User-Controlled Key
CVSS: 5.3
CVSS V4 Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N
References: https://github.com/blossom-editor/blossom/issues/214
https://github.com/blossom-editor/blossom/blob/v1.17.1/blossom-backend/backend/src/main/java/com/blossom/backend/server/picture/PictureService.java#L222-L232
https://github.com/blossom-editor/blossom/blob/v1.17.1/blossom-backend/backend/src/main/java/com/blossom/backend/server/picture/PictureController.java#L56-L109
https://hackmd.io/@hieuPenguinnn/blossom-picture-idor-cross-user-delete
https://github.com/blossom-editor/blossom
Credit: hieuPenguinnn
Description: Blossom through 1.17.1 contains an authorization bypass vulnerability that allows authenticated non-readonly users to modify other users' pictures by supplying arbitrary picture ids. Attackers can call the picture delete, /picture/del/batch, or /picture/star endpoints to permanently delete victims' images and stored files or change their star status.

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