Auth bypass in Harnessrouter
CVE-2026-125331
HarnessRouter is a self-hosted unified API for running agent harnesses with sessions, streaming, files, cancellation, and failure handling. Prior to 0.31.8, a console that is not in self-hosted mode attaches the server's internal key to requests carrying an Authorization header before validating the bearer, while the service-only PUT and GET /v1/orgs/{org}/connections/{name}, PUT /v1/orgs/{org}/policy/{backend}, and /internal/* routes trust that key and take the organization from the URL. In a multi-organization deployment, a remote caller can use a made-up bearer to rewrite another organization's provider connection to an attacker-controlled endpoint, causing later prompts to be disclosed and attacker-controlled responses to influence tasks. This issue is fixed in version 0.31.8.
Vulnerability class: Broken Access Control
Published .
CVSS v3 metric
CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Harnessrouter — versions < 0.31.8
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-125331?
- CVE-2026-125331 is a critical-severity vulnerability in Harnessrouter, classified under Missing Authorization. CVSS score: 9.1/10. Published 2026-11-10.
- How severe is CVE-2026-125331?
- Critical severity. CVSS v3 base score is 9.1 out of 10.