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High, CVSS 7.5amended

Steeltoe.Discovery.Consul: malformed 'secure' metadata aborts service instance lookup (DoS)

CVE-2026-81516GHSA-67c9-f6v2-qv86

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (steeltoe.discovery.consul 4.3.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
  • CVE-2026-81516: 0.61% estimated exploitation activity in the next 30 days; percentile 49.21 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary Steeltoe's Consul discovery client parses the secure metadata field on each registered service instance using bool.Parse, which throws on any value other than true or false. A single service instance registered with a malformed secure value (for example yes or 1) aborts construction of the entire instance list for that service, making the service undiscoverable. When GetAllInstancesAsync is used, one malformed instance in any service can abort enumeration across all services. This is the same "one malformed field aborts the whole batch" availability class as CVE-2026-50196, but affecting the Consul discovery client. Impact Any principal that can register a service in the Consul catalog can trigger a service-discovery outage for all Steeltoe applications resolving that service. The outage affects all instances of the targeted service — not just the malformed one — and persists until the offending registration is removed. Affected configuration - Application uses…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-67c9-f6v2-qv86

  2. Revision 1 · created ·

    Published from osv record GHSA-67c9-f6v2-qv86

Agent brief

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# Patch Next advisory brief: CVE-2026-81516

Advisory: Steeltoe.Discovery.Consul: malformed 'secure' metadata aborts service instance lookup (DoS)
IDs: CVE-2026-81516, GHSA-67c9-f6v2-qv86
Record: https://patchnext.com/advisories/cve-2026-81516 (revision 2, source checked 26 Oct 2026, 17:05 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: steeltoe.discovery.consul 4.3.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- NuGet steeltoe.discovery.consul: affected >= 4.0.0, <= 4.2.0; fixed in 4.3.0

## Suggested inspection (read-only)
- NuGet steeltoe.discovery.consul: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on steeltoe.discovery.consul.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-67c9-f6v2-qv86 (OSV record GHSA-67c9-f6v2-qv86 lists affected ranges: NuGet steeltoe.discovery.consul >=4.0.0 <4.3.0 (fixed))
- Verified: https://github.com/advisories/GHSA-67c9-f6v2-qv86 (GitHub-reviewed advisory GHSA-67c9-f6v2-qv86 lists affected ranges: NuGet steeltoe.discovery.consul >=4.0.0 <=4.2.0)

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