PHP · SEPTEMBER 2026 · EARLY WARNING

Issabel Framework Vulnerability: Critical JWT Signing Key Issue

EARLY WARNING · UNCONFIRMED. This page describes a developing threat that 0Day surfaced from early signals and has not yet independently confirmed. Details may change. Always verify against the primary sources before acting.
Severity
CRITICAL
CVSS
9.8
Affected component
isabell framework (other)
Patched version
Not yet available
CVE-2026-89026

The Issabel Framework, which supports Issabel PBX software, reportedly contains a hard-coded HS256 JWT signing key. This allows unauthenticated remote attackers to forge valid bearer tokens and execute arbitrary OS commands as the Asterisk user.

What happened

An early warning has been issued for a critical vulnerability in the Issabel Framework. The vulnerability involves a hard-coded HS256 JWT signing key. This key allows unauthenticated remote attackers to forge valid bearer tokens. Attackers can use these tokens to execute arbitrary OS commands as the Asterisk user. The vulnerability is currently being exploited in the wild.

The Issabel Framework is a component of the Issabel PBX software. The specific version range affected by this vulnerability has not been published yet. Users should monitor official sources for updates on affected versions and patches.

What to do about it

How 0Day would have caught this

MATCHED TO YOUR ACTUAL DEPENDENCY GRAPH0Day matches every incoming threat signal against your GitHub organization’s full dependency graph, including transitive dependencies. If isabell framework is anywhere in your dependency tree, the engineers who own the affected repositories get a push alert the moment it is flagged — no manual audit to remember to run.

Read how this differs from waiting on a scanner to catch a known advisory, or see the exact, read-only access 0Day needs to do this for an organization.

Frequently asked questions

Am I affected?

If you are using the Issabel Framework, you may be affected. The specific version range has not been published yet. Monitor official sources for updates.

What should I do right now?

Check your Issabel Framework installation for any signs of unauthorized activity. Monitor official sources for updates on the vulnerability and any published patches.

Has this been exploited in the wild?

Yes, the vulnerability is reportedly being exploited in the wild.

Sources

Join the 0Day waitlist →

← Back to all threats