CVE-2026-27193: @feathersjs/authentication oauth Feathers Exposes Internal Headers Vulnerability

HIGH
Advisory Identifier: GHSA-9m9c-vpv5-9g85
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CWE-200
Published
Advisory Summary

CVE-2026-27193 is a HIGH feathers exposes internal headers vulnerability (CWE-200: Exposure of Sensitive Information to an Unauthorized Actor) affecting @feathersjs/authentication oauth libraries in the npm ecosystem. The issue involves feathers exposes internal headers via unencrypted session cookie. Remediation is available by upgrading affected packages to version 5.0.40.

CVE-2026-27193 at a Glance

CVE Identifier CVE-2026-27193
GHSA Identifier GHSA-9m9c-vpv5-9g85
Severity HIGH
CVSS v3.1 Base Score N/A
CWE Classification CWE-200: Exposure of Sensitive Information to an Unauthorized Actor
Affected Product @feathersjs/authentication oauth
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-27193

To remediate this vulnerability, upgrade all affected @feathersjs/authentication oauth dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

@feathersjs/authentication-oauth fixed: 5.0.40 
npm install @feathersjs/authentication-oauth@5.0.40
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls @feathersjs/authentication-oauth

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-27193, inspect your project dependencies using npm:

npm ls @feathersjs/authentication-oauth

Analyze the terminal output to locate any version of @feathersjs/authentication oauth in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.0.40), your application is affected.

Note: The npm ls @feathersjs/authentication-oauth command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor, where the product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. In @feathersjs/authentication oauth, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

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: ```javascript // https://github.com/feathersjs/feathers/blob/dove/packages/authentication-oauth/src/service.ts#L173 session.headers = headers; ``` 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. **Credits**: Abdelwahed Madani Yousfi (@vvxhid) / Edoardo Geraci (@b0-n0-b0) / Thomas Rinsma (@ThomasRinsma) From Codean Labs.

CVE-2026-27193 Affected @feathersjs/authentication oauth Versions

1 component(s)
Fixed Versions:
5.0.40
Product / Package Ecosystem Affected Versions Fixed Version
@feathersjs/authentication-oauth
npm/@feathersjs/authentication-oauth
npm
< 5.0.40
5.0.40

References

GitHub Advisory / Wiki ADVISORY
https://github.com/feathersjs/feathers/security/advisories/GHSA-9m9c-vpv5-9g85
NVD — CVE-2026-27193 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-27193
Security Fix Commit FIX COMMIT
https://github.com/feathersjs/feathers/commit/ee19a0ae9bc2ebf23b1fe598a1f7361981b65401
@feathersjs/authentication oauth Source Repository REPOSITORY
https://github.com/feathersjs/feathers
@feathersjs/authentication oauth Release RELEASE
https://github.com/feathersjs/feathers/releases/tag/v5.0.40

Frequently Asked Questions

What is CVE-2026-27193?
CVE-2026-27193 is a security vulnerability in @feathersjs/authentication oauth involving Feathers exposes internal headers via unencrypted session cookie under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor.
Which @feathersjs/authentication oauth versions are affected?
Affected versions include releases prior to 5.0.40 across affected packages: @feathersjs/authentication-oauth.
What version fixes CVE-2026-27193?
Upgrading to 5.0.40 (or the latest patched release for your respective branch) resolves the vulnerability.
Is @feathersjs/authentication-oauth affected?
Yes, @feathersjs/authentication-oauth is affected in releases prior to 5.0.40. Upgrade your dependency to 5.0.40 or later.
What CWE is associated with CVE-2026-27193?
CVE-2026-27193 is classified under CWE-200: Exposure of Sensitive Information to an Unauthorized Actor (The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.).
How can I check npm dependencies for CVE-2026-27193?
Run the dependency tree command: 'npm ls @feathersjs/authentication-oauth'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-9m9c-vpv5-9g85",
  "modified" : "2026-02-23T22:26:49Z",
  "published" : "2026-02-19T20:32:37Z",
  "aliases" : [ "CVE-2026-27193" ],
  "summary" : "Feathers exposes internal headers via unencrypted session cookie",
  "details" : "All HTTP request headers are stored in the session cookie, which is signed but not encrypted, exposing internal proxy/gateway headers to clients.\n\nThe OAuth service stores the complete headers object in the session:\n```javascript\n// https://github.com/feathersjs/feathers/blob/dove/packages/authentication-oauth/src/service.ts#L173\nsession.headers = headers;\n```\n\nThe 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.\n\nUnder 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.\n\n**Credits**:  Abdelwahed Madani Yousfi (@vvxhid) / Edoardo Geraci (@b0-n0-b0) / Thomas Rinsma (@ThomasRinsma) From Codean Labs.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@feathersjs/authentication-oauth"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "5.0.40"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 5.0.39"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/feathersjs/feathers/security/advisories/GHSA-9m9c-vpv5-9g85"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-27193"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/feathersjs/feathers/commit/ee19a0ae9bc2ebf23b1fe598a1f7361981b65401"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/feathersjs/feathers"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/feathersjs/feathers/releases/tag/v5.0.40"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-200" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-19T20:32:37Z",
    "nvd_published_at" : "2026-02-21T05:17:28Z"
  }
}