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HIGH severity

CVE-2026-45720

HIGH

CVE-2026-45720 is a high-severity (CVSS 7) vulnerability in github.com/siderolabs/omni. O3 Security confirms whether CVE-2026-45720 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Omni has a TOCTOU race condition that allows multiple concurrent uses of a single-use SAML session token

Also known asGO-2026-5160
Published
Jun 5, 2026
Updated
Jun 25, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Jun 25, 2026 · OSV.dev, FIRST.org (EPSS)

Real-World Exposure

2 pkgs affected
🐹github.com/siderolabs/omni🐹github.com/siderolabs/omni

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Summary

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.

Severity

  • Attack Vector: Local: the attacker needs to either be able to intercept the local, unencrypted traffic or needs access to user's browser.
  • 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).
  • Privileges Required: None: no Omni account is required to carry out the race once the session token is in hand.
  • User Interaction: Required: the victim must initiate a SAML authentication flow to produce the session token that the attacker intercepts.
  • Scope: Unchanged: the impact stays within Omni's authorization boundary.
  • Confidentiality Impact: High: successful exploitation authenticates the attacker as the victim's email identity, granting read access to any resource accessible to that identity.
  • 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.
  • 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.

Impact

  • Session replay: A stolen saml-session token can be used more than once, defeating its single-use guarantee.
  • 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.
  • Authentication as victim: Any gRPC endpoint gated by the SAML interceptor can be reached as the victim's email identity during the race window.
  • Audit log pollution: Each raced call generates an audit entry attributed to the victim's email, obscuring the attacker's actions.

Credit

This vulnerability was discovered and reported by bugbunny.ai.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/siderolabs/omniall versions1.6.6
🐹Gogithub.com/siderolabs/omni≥ 1.7.0&&< 1.7.31.7.3

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/siderolabs/omni. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update github.com/siderolabs/omni to 1.6.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45720 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 pinpoints whether CVE-2026-45720 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-45720. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Summary `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. ## Severity - **Attack Vector:*
O3 Security · Impact-Aware SCA

Is CVE-2026-45720 in your dependencies?

O3 detects CVE-2026-45720 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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