TI-2026-21630 Aliases CVE-2026-27193 GHSA-9m9c-vpv5-9g85

Feathers exposes internal headers via unencrypted session cookie

LOW 36CWE-200Published 2026-02-21 · Updated 2026-02-25

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: High
Attack requirements: Present
Impact type: Information disclosure
Confidentiality · integrity · availability: High · None · None
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-200.

Summary

Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In versions 5.0.39 and below, all HTTP request headers are stored in the session cookie, which is signed but not encrypted, exposing internal proxy/gateway headers to clients. The OAuth service stores the complete headers object in the session, then the session is persisted using cookie-session, which base64-encodes the data. While the cookie is signed to prevent tampering, the contents are readable by anyone by simply decoding the base64 value. Under specific deployment configurations (e.g., behind reverse proxies or API gateways), this can lead to exposure of sensitive internal infrastructure details such as API keys, service tokens, and internal IP addresses. This issue has been fixed in version 5.0.40.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00398 34th percentileScored 2026-11-07

Fix Fixed feathers (feathersjs): 5.0.40@feathersjs/authentication-oauth (npm): 5.0.40

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

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
feathersjs	feathers	before 5.0.40	5.0.40	Patch available	CNA
—	@feathersjs/authentication-oauth (npm)	before 5.0.40	5.0.40	Patch available	GHSA-9m9c-vpv5-9g85

feathers Vendorfeathersjs Affected before 5.0.40 Fixed in 5.0.40 Patch available CNA
@feathersjs/authentication-oauth (npm) Vendor— Affected before 5.0.40 Fixed in 5.0.40 Patch available GHSA-9m9c-vpv5-9g85

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:feathersjs:feathers::::::node.js::*	before 5.0.40	Vulnerable	feathersjs

cpe:2.3:a:feathersjs:feathers:*:*:*:*:*:node.js:*:* Versions before 5.0.40 Vulnerable ·feathersjs

Remediation

Fix · CNA feathers (feathersjs) Fixed in 5.0.40
Fix · GHSA-9m9c-vpv5-9g85 @feathersjs/authentication-oauth (npm) Fixed in 5.0.40 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-27193
2026-10-03 Alias added: GHSA-9m9c-vpv5-9g85

References

Patch 1

https://github.com/feathersjs/feathers/commit/ee19a0ae9bc2ebf23b1fe598a1f7361981b65401

Advisory 2

Other 2

TI-2023-19332 feathersjs socket handler allows abusing implicit toString CVSS 3.1HIGH 7.5
TI-2026-23379 NoSQL Injection via WebSocket id Parameter in MongoDB Adapter CVSS 4.0CRITICAL 9.3
TI-2026-23378 Feathersjs has an OAuth Callback Account Takeover CVSS 4.0CRITICAL 9.3
TI-2026-21629 Feathers has an origin validation bypass via prefix matching CVSS 4.0HIGH 7.6
TI-2026-21628 Feathers: Open Redirect in OAuth callback enables account takeover CVSS 4.0HIGH 7.4

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences