Is CVE-2026-77426 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-77426 being exploited in the wild.

How severe is CVE-2026-77426?

High severity, with a CVSS score of 4, published 22 September 2026.

Which products and versions are affected?

unleash-server (npm) < 8.0.3, SEMVER:introduced=0,fixed=8.0.3; Unleash <5.9.0.

Is there a fix for CVE-2026-77426?

Yes. unleash-server (npm): upgrade to 8.0.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-77426 attacked?

It is attacked over the network, in a web application.

Am I affected by CVE-2026-77426?

Check whether you run unleash-server (npm) or Unleash at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-77426: Unleash admin API missing await on permission check and cross-project IDOR

Q: Is there a fix for CVE-2026-77426?

Yes. unleash-server (npm): upgrade to 8.0.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

Q: How is CVE-2026-77426 attacked?

It is attacked over the network, in a web application.

Q: Am I affected by CVE-2026-77426?

Check whether you run unleash-server (npm) or Unleash at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-77426 · Severity: high · CVSS 4 · Published 2026-09-22

Unleash is a feature management platform that controls feature toggles and deployment settings across projects. Multiple authorization flaws in its admin API allow authenticated users to bypass permission checks and access data from arbitrary projects, including modifying segment assignments, reading variant configurations, and changing feature tags across organizational boundaries. This completely undermines the project isolation model that governs multi-tenant deployments.

Technologies: unleash-server (npm), Unleash. Vendors: npm, Unleash.

Quick answers

Is CVE-2026-77426 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-77426 being exploited in the wild.
How severe is CVE-2026-77426?: High severity, with a CVSS score of 4, published 22 September 2026.
Which products and versions are affected?: unleash-server (npm) < 8.0.3, SEMVER:introduced=0,fixed=8.0.3; Unleash <5.9.0.
Is there a fix for CVE-2026-77426?: Yes. unleash-server (npm): upgrade to 8.0.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-77426 attacked?: It is attacked over the network, in a web application.
Am I affected by CVE-2026-77426?: Check whether you run unleash-server (npm) or Unleash at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

unleash-server (npm): upgrade to 8.0.3 or later
```
npm install unleash-server@8.0.3
```

Technical details

The vulnerabilities stem from five distinct authorization failures in the admin API. The most critical is a missing `await` on an async permission check in the segment-controller (POST /api/admin/segments/strategies): the code calls `hasPermission()` but neglects to await the returned Promise, causing the truthy Promise object to always pass the conditional guard, completely bypassing the UPDATE_FEATURE_STRATEGY permission validation. The remaining four are insecure direct object references (IDOR) where API endpoints fail to validate that requested resources belong to the specified project: variants endpoint ignores projectId entirely, strategies endpoint ignores all parameters except strategyId, environment-info endpoint lacks ownership validation, and tag-modification endpoint accepts feature arrays without verifying project membership. All require only authentication (no special privilege) to exploit. Patches adding await and proper ownership checks are available.

Affected products

Unleash Unleash <5.9.0

Identifiers

CVE-2026-77426
GHSA-72h8-wp98-7hch

Timeline

2026-09-22: disclosed
other: CVE-2026-77426 assigned

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