Bytebase 0.12.0 before 1.0.1 contains an authentication bypass vulnerability that allows unauthenticated attackers to log in as any user. The flaw stems from trusting client-supplied GitLab provider configuration in the POST /api/auth/login/GITLAB_SELF_HOST endpoint. Attackers can set instanceUrl to a server they control that returns an active user with a chosen email. Bytebase then issues session tokens for that principal, letting attackers impersonate existing users including the Owner or create new members.
https://github.com/bytebase/bytebase/security/advisories/GHSA-5r3p-6rj5-7937
https://github.com/bytebase/bytebase/releases/tag/1.0.1
https://github.com/bytebase/bytebase/pull/834
https://github.com/bytebase/bytebase/commit/d69e682243b25b51dd52912a26e2f259b5f3db2d
https://github.com/bytebase/bytebase/blob/1.0.0/server/auth.go#L79-L93
Published: 2026-10-22
Updated: 2026-10-22
Base Score: 10
Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C
Severity: Critical
Base Score: 9.8
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: Critical
Base Score: 9.3
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: Critical