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CVE-2026-81516 high CVSS 7.5

Vulnerability in Steeltoe.Discovery.Consul (CVE-2026-81516)

Summary

Vulnerability in Steeltoe.Discovery.Consul (CVE-2026-81516). Risk of unauthorized operations or information disclosure. Exploitable via secure. Mitigation: upgrade to 4.3.0 or later.

Original description

The description as published by the source.

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 ConsulDiscoveryClient (any deployment).
  • The Consul catalog contains at least one service instance with a secure metadata value that is not true or false.
  • Mixed-platform environments where non-.NET clients register services with non-standard metadata values are more likely to encounter this condition.

Mitigations

If an immediate upgrade is not possible:

  • Audit the Consul catalog for service registrations with no…

Source: NIST National Vulnerability Database NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-81516 has been found in Steeltoe.Discovery.Consul.
Attackers can target a specific entry point like secure over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade Steeltoe.Discovery.Consul to 4.3.0 or later.
If unsure, ask your IT team or search "Steeltoe.Discovery.Consul CVE-2026-81516" on the vendor's site.

CVE-2026-81516 (Steeltoe.Discovery.Consul) — CWE-755 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: secure / bool.Parse / true / false
Patched: 4.3.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-755) exists in Steeltoe.Discovery.Consul. Attackers reach the vulnerable code path via secure without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of Steeltoe.Discovery.Consul. Attack surface: secure / bool.Parse / true / false.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 4.3.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'Steeltoe.Discovery.Consul' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    grep -r 'Steeltoe.Discovery.Consul' . | grep -v node_modules

    リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で Steeltoe.Discovery.Consul を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade Steeltoe.Discovery.Consul to 4.3.0

    ステージング環境で 4.3.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

nuget Steeltoe.Discovery.Consul
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.3.0"}]}]

References

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