Vulnerability-Lookup

CVE-2026-73500 (GCVE-0-2026-73500)

Vulnerability from cvelistv5 – Published: 2026-08-12 21:22 – Updated: 2026-08-12 21:22

Title

etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline

Summary

etcd is a distributed key-value store for the data of a distributed system. Prior to versions 3.5.33, 3.6.14, and 3.7.1, a network attacker who can reach an etcd TLS listener can open many TCP connections and never send a ClientHello. In client/pkg/transport/listener_tls.go, each connection handled by tlsListener.acceptLoop spawns a goroutine that blocks indefinitely inside tls.Conn.Handshake() and remains tracked in the pending map. Unbounded goroutine and map growth can exhaust memory in the etcd process, causing loss of availability for the cluster and, when etcd backs Kubernetes, the control plane. This issue is fixed in versions 3.5.33, 3.6.14, and 3.7.1.

Severity

8.7 (High)


                        
                          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

CWE

CWE-770 - Allocation of Resources Without Limits or Throttling

Assigner

GitHub_M

References

9 references

URL	Tags
https://github.com/etcd-io/etcd/security/advisori…	x_refsource_CONFIRM
https://github.com/etcd-io/etcd/pull/22130	x_refsource_MISC
https://github.com/etcd-io/etcd/commit/2e07efce97…	x_refsource_MISC
https://github.com/etcd-io/etcd/commit/89ff6d5079…	x_refsource_MISC
https://github.com/etcd-io/etcd/commit/8e4dd0679a…	x_refsource_MISC
https://github.com/etcd-io/etcd/commit/f73cba7d92…	x_refsource_MISC
https://github.com/etcd-io/etcd/releases/tag/v3.5.33	x_refsource_MISC
https://github.com/etcd-io/etcd/releases/tag/v3.6.14	x_refsource_MISC
https://github.com/etcd-io/etcd/releases/tag/v3.7.1	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
etcd-io	etcd	Affected: < 3.5.33 Affected: >= 3.6.0, < 3.6.14 Affected: >= 3.7.0-alpha.0, < 3.7.1

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JSON

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "etcd",
          "vendor": "etcd-io",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.5.33"
            },
            {
              "status": "affected",
              "version": "\u003e= 3.6.0, \u003c 3.6.14"
            },
            {
              "status": "affected",
              "version": "\u003e= 3.7.0-alpha.0, \u003c 3.7.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "etcd is a distributed key-value store for the data of a distributed system. Prior to versions 3.5.33, 3.6.14, and 3.7.1, a network attacker who can reach an etcd TLS listener can open many TCP connections and never send a ClientHello. In client/pkg/transport/listener_tls.go, each connection handled by tlsListener.acceptLoop spawns a goroutine that blocks indefinitely inside tls.Conn.Handshake() and remains tracked in the pending map. Unbounded goroutine and map growth can exhaust memory in the etcd process, causing loss of availability for the cluster and, when etcd backs Kubernetes, the control plane. This issue is fixed in versions 3.5.33, 3.6.14, and 3.7.1."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "attackComplexity": "LOW",
            "attackRequirements": "NONE",
            "attackVector": "NETWORK",
            "baseScore": 8.7,
            "baseSeverity": "HIGH",
            "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",
            "version": "4.0",
            "vulnAvailabilityImpact": "HIGH",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "NONE"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-770",
              "description": "CWE-770: Allocation of Resources Without Limits or Throttling",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-12T21:22:25.151Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/etcd-io/etcd/security/advisories/GHSA-6vch-q96h-7gc3",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/etcd-io/etcd/security/advisories/GHSA-6vch-q96h-7gc3"
        },
        {
          "name": "https://github.com/etcd-io/etcd/pull/22130",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/etcd-io/etcd/pull/22130"
        },
        {
          "name": "https://github.com/etcd-io/etcd/commit/2e07efce9745004eb4773cffaada9b5cdf77cff2",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/etcd-io/etcd/commit/2e07efce9745004eb4773cffaada9b5cdf77cff2"
        },
        {
          "name": "https://github.com/etcd-io/etcd/commit/89ff6d50796049d4f1136915ba21504b76e7e372",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/etcd-io/etcd/commit/89ff6d50796049d4f1136915ba21504b76e7e372"
        },
        {
          "name": "https://github.com/etcd-io/etcd/commit/8e4dd0679a2c6b095d2a32a749fda2521c7809a3",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/etcd-io/etcd/commit/8e4dd0679a2c6b095d2a32a749fda2521c7809a3"
        },
        {
          "name": "https://github.com/etcd-io/etcd/commit/f73cba7d920019f91a1ea1f6697833e42731f057",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/etcd-io/etcd/commit/f73cba7d920019f91a1ea1f6697833e42731f057"
        },
        {
          "name": "https://github.com/etcd-io/etcd/releases/tag/v3.5.33",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/etcd-io/etcd/releases/tag/v3.5.33"
        },
        {
          "name": "https://github.com/etcd-io/etcd/releases/tag/v3.6.14",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/etcd-io/etcd/releases/tag/v3.6.14"
        },
        {
          "name": "https://github.com/etcd-io/etcd/releases/tag/v3.7.1",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/etcd-io/etcd/releases/tag/v3.7.1"
        }
      ],
      "source": {
        "advisory": "GHSA-6vch-q96h-7gc3",
        "discovery": "UNKNOWN"
      },
      "title": "etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-73500",
    "datePublished": "2026-08-12T21:22:25.151Z",
    "dateReserved": "2026-08-12T19:00:33.736Z",
    "dateUpdated": "2026-08-12T21:22:25.151Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-73500\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-12T22:17:17.290\",\"lastModified\":\"2026-08-12T22:17:17.290\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"etcd is a distributed key-value store for the data of a distributed system. Prior to versions 3.5.33, 3.6.14, and 3.7.1, a network attacker who can reach an etcd TLS listener can open many TCP connections and never send a ClientHello. In client/pkg/transport/listener_tls.go, each connection handled by tlsListener.acceptLoop spawns a goroutine that blocks indefinitely inside tls.Conn.Handshake() and remains tracked in the pending map. Unbounded goroutine and map growth can exhaust memory in the etcd process, causing loss of availability for the cluster and, when etcd backs Kubernetes, the control plane. This issue is fixed in versions 3.5.33, 3.6.14, and 3.7.1.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"etcd-io\",\"product\":\"etcd\",\"versions\":[{\"version\":\"\u003c 3.5.33\",\"status\":\"affected\"},{\"version\":\"\u003e= 3.6.0, \u003c 3.6.14\",\"status\":\"affected\"},{\"version\":\"\u003e= 3.7.0-alpha.0, \u003c 3.7.1\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"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:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X\",\"baseScore\":8.7,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"attackRequirements\":\"NONE\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"references\":[{\"url\":\"https://github.com/etcd-io/etcd/commit/2e07efce9745004eb4773cffaada9b5cdf77cff2\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/etcd-io/etcd/commit/89ff6d50796049d4f1136915ba21504b76e7e372\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/etcd-io/etcd/commit/8e4dd0679a2c6b095d2a32a749fda2521c7809a3\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/etcd-io/etcd/commit/f73cba7d920019f91a1ea1f6697833e42731f057\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/etcd-io/etcd/pull/22130\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/etcd-io/etcd/releases/tag/v3.5.33\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/etcd-io/etcd/releases/tag/v3.6.14\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/etcd-io/etcd/releases/tag/v3.7.1\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/etcd-io/etcd/security/advisories/GHSA-6vch-q96h-7gc3\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}

GHSA-6VCH-Q96H-7GC3

Vulnerability from github – Published: 2026-07-24 22:40 – Updated: 2026-08-12 21:22

Summary

etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline

Details

Impact

What kind of vulnerability is it? Who is impacted?

A network attacker who can reach an etcd TLS listener can open many TCP connections and never send a ClientHello. Each connection spawns a goroutine in the etcd server process that blocks indefinitely inside tls.Conn.Handshake(), and each is tracked in the pending map. Unbounded goroutine and map growth exhausts memory in the etcd process, causing loss of availability for the etcd cluster (and, when etcd backs Kubernetes, the control plane).

Patches

Has the problem been patched? What versions should users upgrade to?

This vulnerability is patched in the following versions:

etcd 3.7.1
etcd 3.6.14
etcd 3.5.33

Workarounds

Is there a way for users to fix or remediate the vulnerability without upgrading?

If upgrading is not immediately possible, then restrict network access. Limit which hosts can reach etcd's client (gRPC) port via firewall rules or network policy, reducing who can attempt exploitation.

Reporter

VMware By Broadcom

Severity

8.7 (High)


                  
                    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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "go.etcd.io/etcd/v3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.7.0-alpha.0"
            },
            {
              "fixed": "3.7.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "go.etcd.io/etcd/v3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.6.0"
            },
            {
              "fixed": "3.6.14"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "go.etcd.io/etcd/v3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.5.33"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-73500"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-24T22:40:16Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nA network attacker who can reach an etcd TLS listener can open many TCP connections and never send a ClientHello. Each connection spawns a goroutine in the etcd server process that blocks indefinitely inside tls.Conn.Handshake(), and each is tracked in the pending map. Unbounded goroutine and map growth exhausts memory in the etcd process, causing loss of availability for the etcd cluster (and, when etcd backs Kubernetes, the control plane).\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\nThis vulnerability is patched in the following versions:\n\n- etcd 3.7.1\n- etcd 3.6.14\n- etcd 3.5.33\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\nIf upgrading is not immediately possible, then restrict network access. Limit which hosts can reach etcd\u0027s client (gRPC) port via firewall rules or network policy, reducing who can attempt exploitation.\n\n### Reporter\n\nVMware By Broadcom",
  "id": "GHSA-6vch-q96h-7gc3",
  "modified": "2026-08-12T21:22:30Z",
  "published": "2026-07-24T22:40:16Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/etcd-io/etcd/security/advisories/GHSA-6vch-q96h-7gc3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/etcd-io/etcd/pull/22130"
    },
    {
      "type": "WEB",
      "url": "https://github.com/etcd-io/etcd/commit/2e07efce9745004eb4773cffaada9b5cdf77cff2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/etcd-io/etcd/commit/f73cba7d920019f91a1ea1f6697833e42731f057"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/etcd-io/etcd"
    },
    {
      "type": "WEB",
      "url": "https://github.com/etcd-io/etcd/releases/tag/v3.5.33"
    },
    {
      "type": "WEB",
      "url": "https://github.com/etcd-io/etcd/releases/tag/v3.6.14"
    },
    {
      "type": "WEB",
      "url": "https://github.com/etcd-io/etcd/releases/tag/v3.7.1"
    }
  ],
  "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline"
}

Sightings

Author	Source	Type	Date	Other

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

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