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CVE-2026-24000 medium CVSS 5.3

Vulnerability in github.com/fleetdm/fleet/v4 (CVE-2026-24000)

Summary

Vulnerability in github.com/fleetdm/fleet/v4 (CVE-2026-24000). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 4.80.1 or later.

Original description

The description as published by the source.

Impact

Fleet trusted client-supplied IP address headers when determining the source IP for incoming requests. This allowed authenticated and unauthenticated clients to spoof their apparent IP address and bypass per-IP rate limiting controls.

Fleet determines a client’s public IP address using HTTP headers such as:

  • X-Forwarded-For
  • X-Real-IP
  • True-Client-IP

These headers were trusted without validation. An attacker could supply arbitrary values in these headers, causing Fleet to treat each request as originating from a different IP address.

This could allow an attacker to bypass per-IP rate limits and increase the effectiveness of brute-force or password-spraying attempts against authentication endpoints.

This issue does not allow authentication bypass, privilege escalation, data exposure, or remote code execution on its own.

Workarounds

Run Fleet behind a trusted reverse proxy or load balancer that overwrites client IP headers.

For more information

If you have any questions or comments about this advisory:

Email us at security@fleetdm.com
Join #fleet in osquery Slack

Credits

We thank @fuzzztf for responsibly reporting this issue.

Source: GitHub Security Advisories (Global) 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-2026-24000 has been found in github.com/fleetdm/fleet/v4.
Risk of unauthorized operations or information disclosure. CVSS score: 5.3/10.
What to do: upgrade github.com/fleetdm/fleet/v4 to 4.80.1 or later.
If unsure, ask your IT team or search "github.com/fleetdm/fleet/v4 CVE-2026-24000" on the vendor's site.

CVE-2026-24000 (github.com/fleetdm/fleet/v4) — CWE-290 / CVSS v3 5.3
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 4.80.1 — apply immediately
Workaround: Run Fleet behind a trusted reverse proxy or load balancer that overwrites client IP headers.
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-290) exists in github.com/fleetdm/fleet/v4.

📍 Affected scope

Check the vendor advisory for the affected versions of github.com/fleetdm/fleet/v4.

🔥 Severity

Severity: Medium (CVSS 5.3/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 4.80.1.

🛡️ Workaround

Workaround: Run Fleet behind a trusted reverse proxy or load balancer that overwrites client IP headers.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'github.com/fleetdm/fleet/v4' . 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 'github.com/fleetdm/fleet/v4' . | 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 github.com/fleetdm/fleet/v4 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 
    Run Fleet behind a trusted reverse proxy or load balancer that overwrites client IP headers.

    パッチが適用されるまでの応急処置として、Run Fleet behind a trusted reverse proxy or load balancer that overwrites client IP headers. 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 github.com/fleetdm/fleet/v4 to 4.80.1

    ステージング環境で 4.80.1 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

go github.com/fleetdm/fleet/v4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.80.1"}]}]

References

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