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Fencer Intel
critical 9.6

CVE-2026-65840 json

Fider: Cross-Tenant Authentication Bypass via Missing tenant_id Filter in getVerificationByKey

published 4mo ago modified 14h ago also GHSA-vxjw-gv4f-vq58 , EUVD-2026-123702

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository getfider/fider. 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
9.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
—
no EPSS score yet
public exploits
0
none known

Summary

Fider is a feedback portal for feature requests and suggestions. Prior to version 0.36.0, in multi-tenant mode (HOST_MODE=multi), an attacker can use an email verification key issued by Tenant A to authenticate as the same email address on Tenant B. This completely bypasses tenant isolation and allows unauthorized account takeover across tenants. Single-host deployments (HOST_MODE=single, the default) are NOT affected. This issue has been patched in version 0.36.0.

Patch / fix

Is CVE-2026-65840 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.

Check with Fencer

CVSS scores

assigned by version score vector
CNA 3.1 9.6 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Affected products

  • getfider fider

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 getfider/fider published their own advisory on GitHub. Reviewed sources take precedence over it.