CVE-2026-40937: RustFS missing admin authorization on notification target endpoints, which allows unauthenticated configuration of event webhooks

Severity: high (CVSS 8.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-04-22 · updated 2026-06-17
Weakness: CWE-862

Description

RustFS is a distributed object storage system built in Rust. Prior to 1.0.0-alpha.94, all four notification target admin API endpoints in `rustfs/src/admin/handlers/event.rs` use a `check_permissions` helper that validates authentication only (access key + session token), without performing any admin-action authorization via `validate_admin_request`. Every other admin handler in the codebase correctly calls `validate_admin_request` with a specific `AdminAction`. This is the only admin handler file that skips authorization. A non-admin user can overwrite a shared admin-defined notification target by name, causing subsequent bucket events to be delivered to an attacker-controlled endpoint. This enables cross-user event interception and audit evasion. 1.0.0-alpha.94 contains a patch.

Affected products

rustfs: 1.0.0-alpha1, 1.0.0-alpha10, 1.0.0-alpha11, 1.0.0-alpha12, 1.0.0-alpha13, 1.0.0-alpha14 (+87)

References

Get alerted when CVE-2026-40937 or the next vulnerability affects your stack