n8n: Cross-Issuer Token Exchange Account Binding via Subject-Only Identity Resolution

## Impact When an n8n instance is configured with more than one trusted token-exchange issuer, external identities are resolved to local accounts using only the JWT `sub` claim, ignoring the issuer (`iss`). As a result, two different issuers that emit the same subject value map to the same local account. An attacker who can obtain a valid token from one trusted issuer with a `sub` matching a victim registered under a different issuer can authenticate as that victim and access their account. This issue only affects instances where the token exchange feature is enabled and more than one trusted external issuer is configured. ## Patches The issue has been fixed in n8n version 2.28.1. Users should upgrade to this version or later to remediate the vulnerability. ## Workarounds If upgrading is not immediately possible, administrators should consider the following temporary mitigations: - If multiple trusted issuers are not required, reduce the token exchange configuration to a single trusted issuer. - Disable the token exchange feature entirely if it is not in active use. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

Source published

22 Jul 2026 21:59:15 UTC

Source modified

22 Jul 2026 22:16:06 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Publisher rating · HIGH