CVE-2026-77426: Unleash Missing Await On Permission Check Vulnerability

Q: What is CVE-2026-77426?

CVE-2026-77426 is a security vulnerability in Unleash involving Missing await on permission check + cross-project IDOR in admin API under CWE-639: Authorization Bypass Through User-Controlled Key.

Q: Which Unleash versions are affected?

Affected versions include releases prior to 8.0.3 across affected packages: unleash-server.

Q: What version fixes CVE-2026-77426?

Upgrading to 8.0.3 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is unleash-server affected?

Yes, unleash-server is affected in releases prior to 8.0.3. Upgrade your dependency to 8.0.3 or later.

Q: What CWE is associated with CVE-2026-77426?

CVE-2026-77426 is classified under CWE-639: Authorization Bypass Through User-Controlled Key (The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.).

Q: How can I check npm dependencies for CVE-2026-77426?

Run the dependency tree command: 'npm ls unleash-server'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

HIGH

Advisory Identifier: GHSA-72h8-wp98-7hch

CWE-639 CWE-862

Published 2026-09-22

Advisory Summary

CVE-2026-77426 is a HIGH missing await on permission check vulnerability (CWE-639: Authorization Bypass Through User-Controlled Key) affecting Unleash libraries in the npm ecosystem. The issue involves missing await on permission check + cross-project idor in admin api. Remediation is available by upgrading affected packages to version 8.0.3.

CVE-2026-77426 at a Glance

CVE Identifier CVE-2026-77426

GHSA Identifier GHSA-72h8-wp98-7hch

Severity HIGH

CVSS v3.1 Base Score N/A

CWE Classification CWE-639: Authorization Bypass Through User-Controlled Key

Affected Product Unleash

Package Ecosystem npm

Published Date 2026-09-22

Last Updated 2026-09-22

How to Fix CVE-2026-77426

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

unleash-server fixed: 8.0.3

npm install unleash-server@8.0.3

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 unleash-server

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-77426, inspect your project dependencies using npm:

npm ls unleash-server

Analyze the terminal output to locate any version of Unleash in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 8.0.3), your application is affected.

Note: The npm ls unleash-server 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-639: Authorization Bypass Through User-Controlled Key, where the system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data. In Unleash, 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

## Summary Multiple authorization vulnerabilities in Unleash admin API, including a critical missing `await` that completely bypasses a permission check. ## Vulnerability 1: Missing `await` on Permission Check (HIGH) **File:** `src/lib/features/segment/segment-controller.ts` (line 345) `POST /api/admin/segments/strategies` has `permission: NONE` at the route level. The handler performs its own check via `this.accessService.hasPermission()`, but **omits the `await` keyword**. Since `hasPermission()` is async (returns `Promise<boolean>`), the variable always receives a truthy Promise object. The `if (!hasFeatureStrategyPermission)` check never triggers. ```typescript // BUG: missing await - hasPermission() returns Promise<boolean> const hasFeatureStrategyPermission = this.accessService.hasPermission( req.user, UPDATE_FEATURE_STRATEGY, projectId, environmentId, ); if (!hasFeatureStrategyPermission) { // Always false - Promise is truthy! res.status(403).send(); return; } ``` **Impact:** Any authenticated user can modify segment assignments on ANY strategy across ALL projects. **Fix:** Add `await`: `const hasFeatureStrategyPermission = await this.accessService.hasPermission(...)` ## Vulnerability 2: Cross-Project Variant Read (MEDIUM) **File:** `src/lib/routes/admin-api/project/variants.ts` (line 213-223) `GET /api/admin/projects/:projectId/features/:featureName/environments/:environment/variants` completely ignores `projectId`. `getVariantsOnEnv()` only uses `featureName` and `environment`. **Impact:** Any authenticated user can read variant configs (names, weights, payloads) from any project. ## Vulnerability 3: Cross-Project Strategy Read (MEDIUM) **File:** `src/lib/features/feature-toggle/feature-toggle-controller.ts` (line 1107-1116) `GET .../strategies/:strategyId` ignores all params except `strategyId`. Any authenticated user can read any strategy's full configuration. ## Vulnerability 4: Cross-Project Environment Info Leak (MEDIUM) **File:** `src/lib/features/feature-toggle/feature-toggle-service.ts` (line 1611) `getEnvironmentInfo()` doesn't validate feature belongs to project. Compare with `getFeature()` which calls `validateFeatureBelongsToProject()`. ## Vulnerability 5: Cross-Project Tag Modification (LOW) **File:** `src/lib/features/feature-toggle/feature-toggle-controller.ts` (line 576-596) `PUT /:projectId/tags` accepts features array in body without validating they belong to projectId.

CVE-2026-77426 Affected Unleash Versions

1 component(s)

Fixed Versions:

8.0.3

Product / Package	Ecosystem	Affected Versions	Fixed Version
unleash-server npm/unleash-server	npm	< 8.0.3	8.0.3

References

GitHub Advisory / Wiki ADVISORY

https://github.com/Unleash/unleash/security/advisories/GHSA-72h8-wp98-7hch

Security Fix Commit FIX COMMIT

https://github.com/Unleash/unleash/commit/7bb2829fc40791aa478e8ffca149c11b0f9cb05a

Security Fix Commit FIX COMMIT

https://github.com/Unleash/unleash/commit/ace121c922d2e3eb6f68d95b0b6ab2fc8d824ea1

Security Fix Commit FIX COMMIT

https://github.com/Unleash/unleash/commit/bea7effd3687425630423f662136d548e100154d

Security Fix Commit FIX COMMIT

https://github.com/Unleash/unleash/commit/c93a963e95e1b7bf1bca2a7729282a48d0eb2f6a

Security Fix Commit FIX COMMIT

https://github.com/Unleash/unleash/commit/dd61d0e10f5977a2e5de78df467c3a17c09fbcef

Unleash Source Repository REPOSITORY

https://github.com/Unleash/unleash

Unleash Release RELEASE

https://github.com/Unleash/unleash/releases/tag/v8.0.3

Frequently Asked Questions

What is CVE-2026-77426?

CVE-2026-77426 is a security vulnerability in Unleash involving Missing await on permission check + cross-project IDOR in admin API under CWE-639: Authorization Bypass Through User-Controlled Key.

Which Unleash versions are affected?

Affected versions include releases prior to 8.0.3 across affected packages: unleash-server.

What version fixes CVE-2026-77426?

Upgrading to 8.0.3 (or the latest patched release for your respective branch) resolves the vulnerability.

Is unleash-server affected?

Yes, unleash-server is affected in releases prior to 8.0.3. Upgrade your dependency to 8.0.3 or later.

What CWE is associated with CVE-2026-77426?

CVE-2026-77426 is classified under CWE-639: Authorization Bypass Through User-Controlled Key (The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.).

How can I check npm dependencies for CVE-2026-77426?

Run the dependency tree command: 'npm ls unleash-server'. 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-72h8-wp98-7hch",
  "modified" : "2026-09-22T20:36:42Z",
  "published" : "2026-09-22T20:36:42Z",
  "aliases" : [ "CVE-2026-77426" ],
  "summary" : "Unleash: Missing await on permission check + cross-project IDOR in admin API",
  "details" : "## Summary\n\nMultiple authorization vulnerabilities in Unleash admin API, including a critical missing `await` that completely bypasses a permission check.\n\n## Vulnerability 1: Missing `await` on Permission Check (HIGH)\n\n**File:** `src/lib/features/segment/segment-controller.ts` (line 345)\n\n`POST /api/admin/segments/strategies` has `permission: NONE` at the route level. The handler performs its own check via `this.accessService.hasPermission()`, but **omits the `await` keyword**. Since `hasPermission()` is async (returns `Promise<boolean>`), the variable always receives a truthy Promise object. The `if (!hasFeatureStrategyPermission)` check never triggers.\n\n```typescript\n// BUG: missing await - hasPermission() returns Promise<boolean>\nconst hasFeatureStrategyPermission = this.accessService.hasPermission(\n    req.user, UPDATE_FEATURE_STRATEGY, projectId, environmentId,\n);\nif (!hasFeatureStrategyPermission) { // Always false - Promise is truthy!\n    res.status(403).send();\n    return;\n}\n```\n\n**Impact:** Any authenticated user can modify segment assignments on ANY strategy across ALL projects.\n\n**Fix:** Add `await`: `const hasFeatureStrategyPermission = await this.accessService.hasPermission(...)`\n\n## Vulnerability 2: Cross-Project Variant Read (MEDIUM)\n\n**File:** `src/lib/routes/admin-api/project/variants.ts` (line 213-223)\n\n`GET /api/admin/projects/:projectId/features/:featureName/environments/:environment/variants` completely ignores `projectId`. `getVariantsOnEnv()` only uses `featureName` and `environment`.\n\n**Impact:** Any authenticated user can read variant configs (names, weights, payloads) from any project.\n\n## Vulnerability 3: Cross-Project Strategy Read (MEDIUM)\n\n**File:** `src/lib/features/feature-toggle/feature-toggle-controller.ts` (line 1107-1116)\n\n`GET .../strategies/:strategyId` ignores all params except `strategyId`. Any authenticated user can read any strategy's full configuration.\n\n## Vulnerability 4: Cross-Project Environment Info Leak (MEDIUM)\n\n**File:** `src/lib/features/feature-toggle/feature-toggle-service.ts` (line 1611)\n\n`getEnvironmentInfo()` doesn't validate feature belongs to project. Compare with `getFeature()` which calls `validateFeatureBelongsToProject()`.\n\n## Vulnerability 5: Cross-Project Tag Modification (LOW)\n\n**File:** `src/lib/features/feature-toggle/feature-toggle-controller.ts` (line 576-596)\n\n`PUT /:projectId/tags` accepts features array in body without validating they belong to projectId.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "unleash-server"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "8.0.3"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/Unleash/unleash/security/advisories/GHSA-72h8-wp98-7hch"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Unleash/unleash/commit/7bb2829fc40791aa478e8ffca149c11b0f9cb05a"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Unleash/unleash/commit/ace121c922d2e3eb6f68d95b0b6ab2fc8d824ea1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Unleash/unleash/commit/bea7effd3687425630423f662136d548e100154d"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Unleash/unleash/commit/c93a963e95e1b7bf1bca2a7729282a48d0eb2f6a"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Unleash/unleash/commit/dd61d0e10f5977a2e5de78df467c3a17c09fbcef"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/Unleash/unleash"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/Unleash/unleash/releases/tag/v8.0.3"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-639", "CWE-862" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-22T20:36:42Z",
    "nvd_published_at" : null
  }
}

CVSS V4

N/A HIGH

Attack Vector N/A

Attack Complexity N/A

Privileges Required N/A

User Interaction N/A

Scope N/A

Confidentiality N/A

Integrity N/A

Availability N/A

Vector String

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

Advisory Metadata

Source ID: GHSA-72h8-wp98-7hch
Schema Version: 1.4.0
Published: 2026-09-22 20:36
Last Modified: 2026-09-22 20:36
Database Record File: advisories/github-reviewed/2026/09/GHSA-72h8-wp98-7hch/GHSA-72h8-wp98-7hch.json