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CVE-2021-37705

Vulnerability in onefuzz (CVE-2021-37705)

Summary

Vulnerability in onefuzz (CVE-2021-37705). Confidential information can be exposed externally. Exploitable via issuer. Mitigation: upgrade to 2.31.0 or later.

Original description

The description as published by the source.

Impact

Starting with OneFuzz 2.12.0 or greater, an incomplete authorization check allows an authenticated user from any Azure Active Directory tenant to make authorized API calls to a vulnerable OneFuzz instance.

To be vulnerable, a OneFuzz deployment must be:

This can result in read/write access to private data such as:

  • Software vulnerability and crash information
  • Security testing tools
  • Proprietary code and symbols

Via authorized API calls, this also enables tampering with existing data and unauthorized code execution on Azure compute resources.

Patches

This issue is resolved starting in release 2.31.0, via the addition of application-level check of the bearer token's issuer against an administrator-configured allowlist.

Workarounds

Users can restrict access to the tenant of a deployed OneFuzz instance < 2.31.0 by redeploying in the default configuration, which omits the --multi_tenant_domain option.

References

You can find an overview of the Microsoft Identity Platform here. This vulnerability applies to the multi-tenant application pattern, as described here.

For more information

If you…

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV

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-2021-37705 has been found in onefuzz.
Attackers can target a specific entry point like issuer over the network to misuse the product.
Confidential information can be exposed externally.
What to do: upgrade onefuzz to 2.31.0 or later.
If unsure, ask your IT team or search "onefuzz CVE-2021-37705" on the vendor's site.

CVE-2021-37705 (onefuzz) — CWE-285
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: issuer
Patched: 2.31.0 — apply immediately
Workaround: Users can restrict access to the tenant of a deployed OneFuzz instance < 2.31.0 by redeploying in the default configuration, which omits the --multi_tenant_domain option.
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-285) exists in onefuzz. Attackers reach the vulnerable code path via issuer without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of onefuzz. Attack surface: issuer.

🔥 Severity

Severity: ?. Confidential information can be exposed externally.

🔧 How to fix

Update to 2.31.0.

🛡️ Workaround

Workaround: Users can restrict access to the tenant of a deployed OneFuzz instance < 2.31.0 by redeploying in the default configuration, which omits the --multi_tenant_domain option.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'onefuzz' . 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 'onefuzz' . | 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 onefuzz 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 temporary workaround mitigate 
    Users can restrict access to the tenant of a deployed OneFuzz instance < 2.31.0 by redeploying in the default configuration, which omits the `--multi_tenant_domain` option.

    パッチが適用されるまでの応急処置として、Users can restrict access to the tenant of a deployed OneFuzz instance < 2.31.0 by redeploying in the default configuration, which omits the --multi_tenant_domain option. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade onefuzz to 2.31.0

    ステージング環境で 2.31.0 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。

  4. 4
    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

PyPI onefuzz
[{"type":"ECOSYSTEM","events":[{"introduced":"2.12.0"},{"fixed":"2.31.0"}]}]

References

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