Vulnerability-Lookup

GHSA-W254-4HP5-7CVV

Vulnerability from github – Published: 2026-03-30 19:22 – Updated: 2026-03-30 19:22

Summary

Fleet vulnerable to Denial of Service via unhandled gRPC log type in launcher endpoint

Details

Summary

A Denial of Service vulnerability in Fleet's gRPC Launcher endpoint allows an authenticated host to crash the entire Fleet server process by sending an unexpected log type value. The server terminates immediately, disrupting all connected hosts, MDM enrollments, and API consumers.

Impact

An attacker with access to a valid Launcher node key can send a specially crafted gRPC request to the Fleet server that triggers an unrecoverable server crash. The gRPC server lacks appropriate error recovery handling, meaning the entire Fleet process terminates rather than gracefully rejecting the malformed input.

Because the crash is instant and repeatable, an attacker could script repeated requests to prevent the server from recovering, resulting in a persistent denial of service until a patched version is deployed.

Workarounds

There is no workaround for this issue other than upgrading to a patched version.

For more information

If there are any questions or comments about this advisory:

Send an email to security@fleetdm.com

Join #fleet in osquery Slack

Credits

Fleet thanks @fuzzztf for responsibly reporting this issue.

Severity ?

6.6 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/fleetdm/fleet/v4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.81.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-34388"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-703"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-30T19:22:39Z",
    "nvd_published_at": "2026-03-27T20:16:35Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nA Denial of Service vulnerability in Fleet\u0027s gRPC Launcher endpoint allows an authenticated host to crash the entire Fleet server process by sending an unexpected log type value. The server terminates immediately, disrupting all connected hosts, MDM enrollments, and API consumers.\n\n### Impact\n\nAn attacker with access to a valid Launcher node key can send a specially crafted gRPC request to the Fleet server that triggers an unrecoverable server crash. The gRPC server lacks appropriate error recovery handling, meaning the entire Fleet process terminates rather than gracefully rejecting the malformed input.\n\nBecause the crash is instant and repeatable, an attacker could script repeated requests to prevent the server from recovering, resulting in a persistent denial of service until a patched version is deployed.\n\n### Workarounds\n\nThere is no workaround for this issue other than upgrading to a patched version.\n\n### For more information\n\nIf there are any questions or comments about this advisory:\n\nSend an email to  [security@fleetdm.com](mailto:security@fleetdm.com)\n\nJoin #fleet in [osquery Slack](https://join.slack.com/t/osquery/shared_invite/zt-h29zm0gk-s2DBtGUTW4CFel0f0IjTEw)\n\n### Credits\n\nFleet thanks @fuzzztf for responsibly reporting this issue.",
  "id": "GHSA-w254-4hp5-7cvv",
  "modified": "2026-03-30T19:22:39Z",
  "published": "2026-03-30T19:22:39Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fleetdm/fleet/security/advisories/GHSA-w254-4hp5-7cvv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-34388"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fleetdm/fleet"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Fleet vulnerable to Denial of Service via unhandled gRPC log type in launcher endpoint"
}

CVE-2026-34388 (GCVE-0-2026-34388)

Vulnerability from cvelistv5 – Published: 2026-03-27 19:13 – Updated: 2026-03-31 13:44

Title

Fleet vulnerable to Denial of Service via unhandled gRPC log type in launcher endpoint

Summary

Fleet is open source device management software. Prior to 4.81.0, a denial-of-service vulnerability in Fleet's gRPC Launcher endpoint allows an authenticated host to crash the entire Fleet server process by sending an unexpected log type value. The server terminates immediately, disrupting all connected hosts, MDM enrollments, and API consumers. Version 4.81.0 patches the issue.

Severity ?

6.6 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U

CWE

CWE-703 - Improper Check or Handling of Exceptional Conditions

Assigner

GitHub_M

References

URL

Tags

https://github.com/fleetdm/fleet/security/advisor…

x_refsource_CONFIRM

Impacted products

	Vendor	Product	Version
	fleetdm	fleet	Affected: < 4.81.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-34388",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-31T13:43:45.848886Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-31T13:44:23.562Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "fleet",
          "vendor": "fleetdm",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 4.81.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Fleet is open source device management software. Prior to 4.81.0, a denial-of-service vulnerability in Fleet\u0027s gRPC Launcher endpoint allows an authenticated host to crash the entire Fleet server process by sending an unexpected log type value. The server terminates immediately, disrupting all connected hosts, MDM enrollments, and API consumers. Version 4.81.0 patches the issue."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 6.6,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-703",
              "description": "CWE-703: Improper Check or Handling of Exceptional Conditions",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-27T19:13:00.388Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/fleetdm/fleet/security/advisories/GHSA-w254-4hp5-7cvv",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/fleetdm/fleet/security/advisories/GHSA-w254-4hp5-7cvv"
        }
      ],
      "source": {
        "advisory": "GHSA-w254-4hp5-7cvv",
        "discovery": "UNKNOWN"
      },
      "title": "Fleet vulnerable to Denial of Service via unhandled gRPC log type in launcher endpoint"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-34388",
    "datePublished": "2026-03-27T19:13:00.388Z",
    "dateReserved": "2026-03-27T13:45:29.619Z",
    "dateUpdated": "2026-03-31T13:44:23.562Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-W254-4HP5-7CVV

Summary

Impact

Workarounds

For more information

Credits

CVE-2026-34388 (GCVE-0-2026-34388)

Tags

Sightings

Nomenclature