Express Gateway OAuth refresh token grant authentication bypass
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- Present
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-287.
Summary
Express Gateway through 1.16.11 has an authentication bypass in its OAuth 2.0 refresh_token grant. The grant fails to validate the token secret or the issuing client (CWE-287). An attacker with any valid client credentials and the identifier part of another user's refresh token can obtain that user's access token and impersonate them against oauth2-protected APIs.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
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.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| ExpressGateway | express-gateway | up to 1.16.11 | — | No fix listed | CNA |
- express-gateway VendorExpressGateway Affected up to 1.16.11 Fixed in — No fix listed CNA
Remediation
The sources list no fixed version for express-gateway.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Timeline
- 2026-10-07 Threatist record created from CVE-2026-107162
- 2026-10-07 Alias added: GHSA-p6v9-9m69-qjxm
- 2026-10-09 Priority changed: MEDIUM → LOW
- 2026-10-10 CISA SSVC decision points changed
- 2026-10-10 Priority changed: LOW → HIGH
References
Other 4
- GitHub Issue #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
More ExpressGateway vulnerabilities
- TI-2026-69129 Express Gateway Hardcoded Default cipherKey Exposes OAuth Tokens CVSS 4.0HIGH 7.4
- TI-2025-08338 ExpressGateway express-gateway REST Endpoint apps.js cross site scripting CVSS 4.0MEDIUM 5.1
- TI-2025-08337 ExpressGateway express-gateway REST Endpoint users.js cross site scripting CVSS 4.0MEDIUM 5.1
- TI-2020-17768 The official Express Gateway Docker images before 1.14.0 contain a blank password for a… CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-107162 · CVE Program
- CVE-2026-107162 · NVD
- FIRST EPSS
- GHSA-p6v9-9m69-qjxm · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences