Is CVE-2026-125331 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-125331 being exploited in the wild.

How severe is CVE-2026-125331?

Critical severity, with a CVSS score of 9.1, published 10 November 2026.

How is CVE-2026-125331 attacked?

It is attacked over the network, in a hosted service.

Am I affected by CVE-2026-125331?

Check whether you run HarnessRouter 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.

CVE-2026-125331: HarnessRouter authentication bypass in API routes

CVE-2026-125331 · Severity: critical · CVSS 9.1 · Published 2026-11-10

HarnessRouter is a self-hosted API platform for running agent tasks and managing provider connections across multiple organizations. In non-self-hosted deployments, an attacker can bypass authentication on critical management routes by sending a fake authorization token alongside the internal service key, allowing them to redirect another organization's connections to attacker-controlled endpoints and intercept or manipulate prompts and responses.

Technologies: HarnessRouter. Vendors: HarnessRouter.

Quick answers

Is CVE-2026-125331 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-125331 being exploited in the wild.
How severe is CVE-2026-125331?: Critical severity, with a CVSS score of 9.1, published 10 November 2026.
Which products and versions are affected?: HarnessRouter before 0.31.8.
Is there a fix for CVE-2026-125331?: Yes: fixed in 0.31.8. Until then: Upgrade to HarnessRouter 0.31.8 or later. For multi-organization deployments, restrict network access to the API routes PUT/GET /v1/orgs/{org}/connections/{name}, PUT /v1/orgs/{org}/policy/{backend}, and /internal/* endpoints to trusted internal services only. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-125331 attacked?: It is attacked over the network, in a hosted service.
Am I affected by CVE-2026-125331?: Check whether you run HarnessRouter 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

Fixed in: 0.31.8

Upgrade to HarnessRouter 0.31.8 or later. For multi-organization deployments, restrict network access to the API routes PUT/GET /v1/orgs/{org}/connections/{name}, PUT /v1/orgs/{org}/policy/{backend}, and /internal/* endpoints to trusted internal services only.

Technical details

The vulnerability exists in multi-organization deployments where the console proxy attaches the internal service key to all requests carrying an Authorization header before bearer token validation occurs. Routes for provider connections, routing policy, and /internal/* endpoints trust possession of the key alone and extract the organization from the URL, but do not verify that the key arrived through a legitimate channel. An attacker with network access can send requests with a fabricated bearer token and the relayed internal key, allowing modification of another organization's configuration. The fix (version 0.31.8) rejects requests that carry both an Authorization header and the internal key, implements constant-time key comparison, and prevents the proxy from forwarding /internal/* routes outside self-hosted mode.

Affected products

HarnessRouter HarnessRouter before 0.31.8

Timeline

2026-11-10: disclosed
2026-10-06: patched: Fix released in version 0.31.8

References

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