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Fencer Intel
high 7.5

CVE-2026-125330 json

HarnessRouter: A workspace's API key could read and change sessions, files and responses of other workspaces in the same organization

published last mo. modified yesterday also EUVD-2026-122786 , GHSA-9pjr-97x3-c4wv

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository HarnessRouter/harnessrouter. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.3%
EPSS 0.3% chance of exploitation in 30 days, percentile 28%
public exploits
0
none known

Summary

HarnessRouter is a self-hosted unified API for agent harnesses. From version 0.4.2 until 0.31.7, routes that accept a session ID or response ID validate only the caller's organization and do not enforce the workspace scope of a non-default workspace API key. A key holder who learns a non-guessable identifier from another workspace in the same organization can read sessions, conversation turns, files, traces, and responses, overwrite files, cancel or delete sessions, and publish share links. The issue does not cross organization boundaries, and console users, organization keys, and Default Workspace keys intentionally retain organization-wide access. This issue is fixed in version 0.31.7.

Patch / fix

Is CVE-2026-125330 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Exploit prediction

0.35% chance of exploitation in the next 30 days, higher than 28% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Inferred packages

No advisory lists a package for this vulnerability yet. The CVE names these as products and links their GitHub repository, and the package registry names the same repository, so they are probably the affected packages. Low confidence: the versions are the CVE’s own for the product, and a stack check reports the package as unchecked when there are none.

ecosystem package repository affected
pypi harnessrouter harnessrouter/harnessrouter
>= 0.4.2, < 0.31.7

Affected products

  • HarnessRouter harnessrouter

Classification

Weakness
  • CWE-639 Authorization Bypass Through User-Controlled Key

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of HarnessRouter/harnessrouter published their own advisory on GitHub. Reviewed sources take precedence over it.