CVE-2026-81516 Steeltoe.Discovery.Consul: malformed 'secure' metadata aborts service instance lookup (DoS)
A malicious service registration with invalid metadata can crash the discovery client, making services undiscoverable in Steeltoe applications.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-81516?
CVE-2026-81516 is a high-severity denial of service vulnerability in SteeltoeOSS security-advisories, published on 17 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Steeltoe is an open source project that provides a collection of libraries that helps users build cloud-native applications. From 4.0.0 until 4.3.0, ConsulDiscoveryClient constructs ConsulServiceInstance objects by parsing each registration's secure metadata with a strict Boolean conversion. A principal that can register a Consul service can supply a secure value other than true or false, causing the exception from one instance to abort construction of the entire instance list and make the targeted service undiscoverable. When GetAllInstancesAsync enumerates all services, one malformed instance can abort enumeration across every service. The outage persists until the offending registration is removed. This issue is fixed in version 4.3.0.
Weakness: CWE-755
Which versions are affected by CVE-2026-81516?
2 open source packages ship an affected version, including Steeltoe.Discovery.Consul.
| Package | Affected | Fixed in |
|---|---|---|
Steeltoe.Discovery.Consul NuGet | From 4.0.0 | 4.3.0 |
Steeltoe.Discovery.Consul NuGet | From 4.0.0 | 4.3.0 |
How do I fix CVE-2026-81516?
Upgrade Steeltoe.Discovery.Consul to 4.3.0 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-81516 being exploited?
There is no known exploitation of CVE-2026-81516 in the wild and no public exploit code.
Sources
Also known as GHSA-67c9-f6v2-qv86.