{"id":"CVE-2026-45720","aliases":["GO-2026-5160"],"url":"https://o3.security/vulnerability/CVE-2026-45720","summary":"Omni has a TOCTOU race condition that allows multiple concurrent uses of a single-use SAML session token","details":"## Summary\n\n`SAML.getSession` (`internal/pkg/auth/interceptor/saml.go`) checks the `Used` flag on a `SAMLAssertion` resource and then marks it used in two separate state operations. Because the check and the update are not atomic, concurrent requests carrying the same `saml-session` token can both observe `Used == false`, both pass validation, and both return a successful authentication context. An attacker who obtains a valid `saml-session` token can exploit this window to authenticate as the token's owner multiple times, defeating the one-time-use guarantee.\n\n## Severity\n\n- **Attack Vector:** Local: the attacker needs to either be able to intercept the local, unencrypted traffic or needs access to user's browser.\n- **Attack Complexity:** High: the attacker must first obtain a valid `saml-session` token belonging to the victim (requires a separate interception step; the token is ephemeral and single-use by design).\n- **Privileges Required:** None: no Omni account is required to carry out the race once the session token is in hand.\n- **User Interaction:** Required: the victim must initiate a SAML authentication flow to produce the session token that the attacker intercepts.\n- **Scope:** Unchanged: the impact stays within Omni's authorization boundary.\n- **Confidentiality Impact:** High: successful exploitation authenticates the attacker as the victim's email identity, granting read access to any resource accessible to that identity.\n- **Integrity Impact:** High: the attacker can confirm one or more public keys under the victim's identity (via `ConfirmPublicKey`), establishing persistent access credentials tied to the victim's account.\n- **Availability Impact:** High: if the attacker can successfully perform the attack and if the victim is a privileged Omni user, e.g., an Omni Operator or Admin, they can take Omni down.\n\n## Impact\n\n- **Session replay**: A stolen `saml-session` token can be used more than once, defeating its single-use guarantee.\n- **Multiple public key confirmations**: An attacker who steals the session can confirm N attacker-controlled public keys under the victim's identity in a single stolen session window, creating N persistent long-lived API credentials tied to the victim's account.\n- **Authentication as victim**: Any gRPC endpoint gated by the SAML interceptor can be reached as the victim's email identity during the race window.\n- **Audit log pollution**: Each raced call generates an audit entry attributed to the victim's email, obscuring the attacker's actions.\n\n## Credit\n\nThis vulnerability was discovered and reported by [bugbunny.ai](https://bugbunny.ai).","published":"2026-06-05T15:25:28Z","modified":"2026-06-25T18:56:27.446022852Z","cvss":{"score":7,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Go","name":"github.com/siderolabs/omni","fixedVersion":"1.6.6"},{"ecosystem":"Go","name":"github.com/siderolabs/omni","fixedVersion":"1.7.3"}],"fix":null,"references":[{"type":"WEB","url":"https://github.com/siderolabs/omni/security/advisories/GHSA-5x9f-6vg5-qg4m"},{"type":"PACKAGE","url":"https://github.com/siderolabs/omni"},{"type":"WEB","url":"https://github.com/siderolabs/omni/releases/tag/v1.6.6"},{"type":"WEB","url":"https://github.com/siderolabs/omni/releases/tag/v1.7.3"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-06-25T18:56:27.446022852Z"}}