Auth bypass in Mlogclub Bbs-Go
CVE-2026-103396
bbs-go through 4.4.6 contains a permission bypass vulnerability in the AdminMiddleware authorization logic where the read-only dashboard.user.view permission rule matches the /api/admin/user/synccount endpoint before the intended dashboard.user.update rule. Authenticated users with only view permissions can call the synccount endpoint to trigger expensive full-table user recounts and cache invalidations, causing denial of service through repeated concurrent database operations.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/mlogclub/bbs-go/issues/303 (issue-tracking)
- github.com/mlogclub/bbs-go/commit/97d0bb3dcbacd686fd5300295afbf4f4a5da7609 (patch)
- github.com/mlogclub/bbs-go/blob/v4.4.6/internal/permissions/admin_permission_re… (technical-description)
- github.com/mlogclub/bbs-go/blob/v4.4.6/internal/handlers/admin/user_handlers.go (technical-description)
- github.com/mlogclub/bbs-go (product)
- www.vulncheck.com/advisories/bbs-go-through-4.4.6-incorrect-authorization-via-a… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-103396?
- CVE-2026-103396 is a medium-severity vulnerability in Mlogclub Bbs-Go, classified under Incorrect Authorization. CVSS score: 4.3/10. Published 2026-09-30.
- How severe is CVE-2026-103396?
- Medium severity. CVSS v3 base score is 4.3 out of 10.