Vulnerability in github.com/fleetdm/fleet/v4 (CVE-2026-26062)
Summary
Vulnerability in github.com/fleetdm/fleet/v4 (CVE-2026-26062). Risk of unauthorized operations or information disclosure. Exploitable via PublishLogs. Mitigation: upgrade to 4.81.0 or later.
Original description
The description as published by the source.
Fleet is open source device management software. Prior to version 4.81.0, Fleet contained a denial-of-service (DoS) issue in the gRPC Launcher PublishLogs endpoint. In affected versions, certain unexpected input values were not handled gracefully, which could cause the Fleet server process to terminate while processing an authenticated request from an enrolled Launcher host. An authenticated attacker with access to any enrolled Launcher node key could cause an immediate and complete denial of service by sending a single gRPC request to the PublishLogs endpoint. This vulnerability impacts availability only. There is no exposure of sensitive data, no authentication bypass, no privilege escalation, and no integrity impact. Version 4.81.0 contains a patch. If upgrading immediately is not possible, the following mitigations can reduce exposure. Restrict network access to the Fleet gRPC endpoint where feasible (for example, limiting inbound access to known host IP ranges); deploy Fleet behind infrastructure that terminates or filters gRPC traffic if Launcher log ingestion is not required; and/or monitor for repeated Fleet process crashes or unexpected restarts indicating potential exploitation.
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-2026-26062 has been found in github.com/fleetdm/fleet/v4.
Attackers can target a specific entry point like PublishLogs over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
What to do: upgrade github.com/fleetdm/fleet/v4 to 4.81.0 or later.
If unsure, ask your IT team or search "github.com/fleetdm/fleet/v4 CVE-2026-26062" on the vendor's site.
CVE-2026-26062 (github.com/fleetdm/fleet/v4) — CWE-20 / CVSS v3 6.5
Attack vector: remote (network-reachable) / no user interaction
Attack surface: PublishLogs
Patched: 4.81.0 — 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.
A vulnerability (CWE-20) exists in github.com/fleetdm/fleet/v4. Attackers reach the vulnerable code path via PublishLogs.
Check the vendor advisory for the affected versions of github.com/fleetdm/fleet/v4. Attack surface: PublishLogs.
Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure.
Update to 4.81.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
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
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1Identify 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。 -
2Apply patch patch
Upgrade github.com/fleetdm/fleet/v4 to 4.81.0ステージング環境で 4.81.0 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。
-
3Post-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
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- web github.com
- web github.com