Executive brief
Sidero Labs Omni, a platform for managing Kubernetes clusters, contains a flaw in how it handles login security tokens. An attacker who intercepts a user's temporary login token can use a high-speed 'race condition' to reuse that token multiple times before the system marks it as expired. This could allow an attacker to impersonate a legitimate user, gain unauthorized access to sensitive data, or establish permanent backdoors into the system.
Technical details
A Time-of-Check Time-of-Use (TOCTOU) race condition exists in the `SAML.getSession` function within `internal/pkg/auth/interceptor/saml.go`. The component checks the `Used` flag on a `SAMLAssertion` and subsequently updates it in non-atomic state operations. By sending concurrent requests using the same `saml-session` token, an attacker can bypass the one-time-use restriction. This allows for session replay, enabling the attacker to authenticate as the victim and potentially confirm multiple attacker-controlled public keys to establish persistent access. Exploitation requires the attacker to intercept ephemeral, unencrypted local traffic or have access to the victim's browser during a SAML authentication flow.
Affected products
- Sidero Labs Omni < 1.6.6, >= 1.7.0, < 1.7.3
Timeline
- 2026-06-05: disclosed
- 2026-06-05: advisory
- 2026-06-05: patched: Patched in versions 1.6.6 and 1.7.3
References
- https://api.github.com/users/bugbunny-research
- https://github.com/bugbunny-research
- https://api.github.com/users/bugbunny-research/gists%7B/gist_id%7D
- https://api.github.com/users/bugbunny-research/repos
- https://avatars.githubusercontent.com/u/262839898?v=4
- https://api.github.com/users/bugbunny-research/events%7B/privacy%7D