CVE-2026-45720: Sidero Labs Omni TOCTOU race condition in SAML session token handling

CVE-2026-45720 · Severity: high · CVSS 7 · Published 2026-09-17

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.

Technologies: github.com/siderolabs/omni (Go), Sidero Labs Omni. Vendors: Go, Sidero Labs.

Quick answers

Is CVE-2026-45720 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-45720 being exploited in the wild.
How severe is CVE-2026-45720?
High severity, with a CVSS score of 7, published 17 September 2026.
Which products and versions are affected?
github.com/siderolabs/omni (Go) SEMVER:introduced=0,fixed=1.6.6, SEMVER:introduced=0,fixed=1.6.6,introduced=1.7.0,fixed=1.7.3; Sidero Labs Omni < 1.6.6, >= 1.7.0, < 1.7.3.
Is there a fix for CVE-2026-45720?
Yes. github.com/siderolabs/omni (Go): upgrade to 1.6.6, 1.7.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-45720 attacked?
It is attacked with local access, in a hosted service.
Am I affected by CVE-2026-45720?
Check whether you run github.com/siderolabs/omni (Go) or Sidero Labs Omni at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • github.com/siderolabs/omni (Go): upgrade to 1.6.6, 1.7.3 or later
    go get github.com/siderolabs/omni@v1.7.3

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

Identifiers

  • CVE-2026-45720
  • GHSA-5x9f-6vg5-qg4m
  • GO-2026-5160

Timeline

  • 2026-06-05: disclosed
  • 2026-06-05: advisory
  • 2026-06-05: patched: Patched in versions 1.6.6 and 1.7.3

References

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