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

Vulnerability from cvelistv5 – Published: 2026-08-12 21:22 – Updated: 2026-08-13 17:53
VLAI
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
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-13 17:49 UTC
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
Impacted products
Vendor Product Version CPE status
etcd-io etcd Affected: < 3.5.33
Affected: >= 3.6.0, < 3.6.14
Affected: >= 3.7.0-alpha.0, < 3.7.1
guessed Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-73500",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-13T17:49:14.567913Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-08-13T17:53:16.094Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "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": "2026-08-13T17:53:16.094Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-73500",
      "date": "2026-09-29",
      "epss": "0.00697",
      "percentile": "0.51144"
    },
    "microsoft_vex": {
      "current_release_date": "2026-08-23T14:54:21.000Z",
      "cve": "CVE-2026-73500",
      "id": "msrc_CVE-2026-73500",
      "initial_release_date": "2026-08-23T14:54:21.000Z",
      "product_status:fixed": "7",
      "product_status:known_affected": "7",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "etcd: `tlsListener.acceptLoop` spawns unbounded handshake goroutines with no deadline",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-73500.json",
      "version": "1"
    },
    "nvd": {
      "cve": {
        "affected": [
          {
            "affectedData": [
              {
                "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"
                  }
                ]
              }
            ],
            "source": "security-advisories@github.com"
          }
        ],
        "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."
          }
        ],
        "id": "CVE-2026-73500",
        "lastModified": "2026-09-18T20:05:53.723",
        "metrics": {
          "cvssMetricV40": [
            {
              "cvssData": {
                "Automatable": "NOT_DEFINED",
                "Recovery": "NOT_DEFINED",
                "Safety": "NOT_DEFINED",
                "attackComplexity": "LOW",
                "attackRequirements": "NONE",
                "attackVector": "NETWORK",
                "availabilityRequirement": "NOT_DEFINED",
                "baseScore": 8.7,
                "baseSeverity": "HIGH",
                "confidentialityRequirement": "NOT_DEFINED",
                "exploitMaturity": "NOT_DEFINED",
                "integrityRequirement": "NOT_DEFINED",
                "modifiedAttackComplexity": "NOT_DEFINED",
                "modifiedAttackRequirements": "NOT_DEFINED",
                "modifiedAttackVector": "NOT_DEFINED",
                "modifiedPrivilegesRequired": "NOT_DEFINED",
                "modifiedSubAvailabilityImpact": "NOT_DEFINED",
                "modifiedSubConfidentialityImpact": "NOT_DEFINED",
                "modifiedSubIntegrityImpact": "NOT_DEFINED",
                "modifiedUserInteraction": "NOT_DEFINED",
                "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
                "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
                "modifiedVulnIntegrityImpact": "NOT_DEFINED",
                "privilegesRequired": "NONE",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
                "subConfidentialityImpact": "NONE",
                "subIntegrityImpact": "NONE",
                "userInteraction": "NONE",
                "valueDensity": "NOT_DEFINED",
                "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",
                "version": "4.0",
                "vulnAvailabilityImpact": "HIGH",
                "vulnConfidentialityImpact": "NONE",
                "vulnIntegrityImpact": "NONE",
                "vulnerabilityResponseEffort": "NOT_DEFINED"
              },
              "source": "security-advisories@github.com",
              "type": "Secondary"
            }
          ],
          "ssvcV203": [
            {
              "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "ssvcData": {
                "id": "CVE-2026-73500",
                "options": [
                  {
                    "exploitation": "none"
                  },
                  {
                    "automatable": "yes"
                  },
                  {
                    "technicalImpact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-13T17:49:14.567913Z",
                "version": "2.0.3"
              }
            }
          ]
        },
        "published": "2026-08-12T22:17:17.290",
        "references": [
          {
            "source": "security-advisories@github.com",
            "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"
          }
        ],
        "sourceIdentifier": "security-advisories@github.com",
        "vulnStatus": "Awaiting Analysis",
        "weaknesses": [
          {
            "description": [
              {
                "lang": "en",
                "value": "CWE-770"
              }
            ],
            "source": "security-advisories@github.com",
            "type": "Secondary"
          }
        ]
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-09-29T16:44:23+00:00",
      "cve": "CVE-2026-73500",
      "id": "CVE-2026-73500",
      "initial_release_date": "2026-08-12T21:22:25.151000+00:00",
      "product_status:fixed": "49",
      "product_status:known_affected": "19",
      "product_status:known_not_affected": "779",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "etcd: etcd: Denial of Service via unbounded TLS handshake goroutines",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-73500.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-13T16:21:44Z",
      "cve": "CVE-2026-73500",
      "id": "CVE-2026-73500",
      "initial_release_date": "2026-08-13T16:21:44Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-73500",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-73500.json",
      "version": "2"
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-73500",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "yes"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-08-13T17:49:14.567913Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-08-13T17:49:15.791Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "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": "2026-08-13T17:53:16.094Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.