# CVE-2026-45720: Omni: TOCTOU race condition allows multiple concurrent uses of a single-use SAML session token

> Attackers can exploit a race condition to reuse single-use SAML tokens, gaining unauthorized access and creating persistent credentials as the victim.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-5x9f-6vg5-qg4m, GO-2026-5160

## What is CVE-2026-45720?

CVE-2026-45720 is a high-severity vulnerability in siderolabs omni, published on 17 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

Omni manages Kubernetes on bare metal, virtual machines, or in a cloud. Prior to 1.6.6 and from 1.7.0 until 1.7.3, SAML.getSession in internal/pkg/auth/interceptor/saml.go checks SAMLAssertion.Used and marks it used in separate state operations. Concurrent requests carrying the same captured saml-session token can each observe the assertion as unused and obtain authentication as the victim before either update is visible. The attacker can invoke SAML-protected gRPC endpoints, use ConfirmPublicKey to create multiple persistent credentials tied to the victim, and generate audit entries attributed to the victim, with the resulting access potentially affecting confidentiality, integrity, and availability according to the victim's privileges. This issue is fixed in versions 1.6.6 and 1.7.3.

Weakness: CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition), CWE-294 (Authentication Bypass by Capture-replay)

## Which versions are affected by CVE-2026-45720?

5 open source packages ship an affected version, including github.com/siderolabs/omni.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/siderolabs/omni` | Go | All versions | 1.6.6, 1.7.3 |
| `github.com/siderolabs/omni` | Go | All versions | 1.6.6 |
| `github.com/siderolabs/omni` | Go | All versions | 1.6.6 |
| `github.com/siderolabs/omni` | Go | From 1.7.0 | 1.7.3 |
| `github.com/siderolabs/omni` | Go | From 1.7.0 | 1.7.3 |

## How do I fix CVE-2026-45720?

Upgrade github.com/siderolabs/omni to a fixed version for your release line: 1.6.6 or 1.7.3.

## Is CVE-2026-45720 being exploited?

There is no known exploitation of CVE-2026-45720 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-45720 and fix it if it is affected.

What it is: CVE-2026-45720 is a high-severity vulnerability in siderolabs omni, published on 17 Sep 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-45720 in the wild and no public exploit code.

Affected packages and fixed versions:
- github.com/siderolabs/omni (Go): affected all versions; fixed in 1.6.6, 1.7.3
- github.com/siderolabs/omni (Go): affected all versions; fixed in 1.6.6
- github.com/siderolabs/omni (Go): affected all versions; fixed in 1.6.6
- github.com/siderolabs/omni (Go): affected from 1.7.0; fixed in 1.7.3
- github.com/siderolabs/omni (Go): affected from 1.7.0; fixed in 1.7.3

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-45720/ (Markdown: https://insights.sbomify.com/CVE-2026-45720/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-45720
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-45720
- OSV: https://osv.dev/vulnerability/CVE-2026-45720

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-45720/
Summaries are generated and may contain mistakes; the official description above is the record.