CVE-2026-103396: Auth Bypass (CVSS 4.3)

Description

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.

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CVSS v3.1 Score

4.3

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

EPSS — Exploit Prediction

0.0029

Probability of exploitation

0.19%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-863 Incorrect Authorization

References

Other References

https://github.com/mlogclub/bbs-go https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/handlers/admin/user_handlers.go#L47-L59 https://github.com/mlogclub/bbs-go/blob/v4.4.6/internal/permissions/admin_permission_registry.go#L59-L60 https://github.com/mlogclub/bbs-go/commit/97d0bb3dcbacd686fd5300295afbf4f4a5da7609 https://github.com/mlogclub/bbs-go/issues/303 https://www.vulncheck.com/advisories/bbs-go-through-4.4.6-incorrect-authorization-via-api-admin-user-synccount

Frequently Asked Questions

What is 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. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-103396? +

CVE-2026-103396 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0029, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-103396? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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