Description
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.
References7
- github.com/bytebase/bytebase
- github.com/bytebase/bytebase/blob/1.0.0/server/auth.go#L79-L93
- github.com/bytebase/bytebase/commit/d69e682243b25b51dd52912a26e…
- github.com/bytebase/bytebase/pull/834
- github.com/bytebase/bytebase/releases/tag/1.0.1
- github.com/bytebase/bytebase/security/advisories/GHSA-5r3p-6rj5…
- www.vulncheck.com/advisories/bytebase-0.12.0-before-1.0.1-authe…
Metrics
- CVSS 3.1
-
9.8
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 4.0
-
9.3
CRITICAL
Score source: CNA
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 1% percentile: 50 · as of 8 November 2026
- CWE
- CWE-290
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.