CVE-2026-56743 (GCVE-0-2026-56743)

Vulnerability from cvelistv5 – Published: 2026-07-15 19:15 – Updated: 2026-07-15 19:15
VLAI
Title
Cilium may unexpectedly allow ingress traffic from the local namespace when a Kubernetes NetworkPolicy is configured with an ipBlock match
Summary
Cilium is a networking, observability, and security solution. From 1.19.0 to 1.19.4, standard Kubernetes NetworkPolicy specifications using CIDR-based ipBlock rules without pod or namespace selectors erroneously generate a wildcard namespace allow rule when Cilium is configured with a custom clusterName rather than the default any value. The parser incorrectly instantiates a pod selector on selectorless peer definitions, allowing traffic from other workloads in the same namespace as the subject of the policy. This issue is fixed in version 1.19.5.
Severity
5.4 (Medium)
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
CWE
  • CWE-863 - Incorrect Authorization
Assigner
References
Impacted products
Vendor Product Version
cilium cilium Affected: >= 1.19.0, < 1.19.5
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "product": "cilium",
          "vendor": "cilium",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.19.0, \u003c 1.19.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Cilium is a networking, observability, and security solution. From 1.19.0 to 1.19.4, standard Kubernetes NetworkPolicy specifications using CIDR-based ipBlock rules without pod or namespace selectors erroneously generate a wildcard namespace allow rule when Cilium is configured with a custom clusterName rather than the default any value. The parser incorrectly instantiates a pod selector on selectorless peer definitions, allowing traffic from other workloads in the same namespace as the subject of the policy. This issue is fixed in version 1.19.5."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "ADJACENT_NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 5.4,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "LOW",
            "privilegesRequired": "LOW",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-863",
              "description": "CWE-863: Incorrect Authorization",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-15T19:15:30.924Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/cilium/cilium/security/advisories/GHSA-fm8w-2m5w-9j7r",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/cilium/cilium/security/advisories/GHSA-fm8w-2m5w-9j7r"
        },
        {
          "name": "https://github.com/cilium/cilium/pull/46305",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cilium/cilium/pull/46305"
        },
        {
          "name": "https://github.com/cilium/cilium/pull/46456",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cilium/cilium/pull/46456"
        },
        {
          "name": "https://github.com/cilium/cilium/commit/1c84ae3b58a7cd54f7ee355e6c524c82f620eae8",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cilium/cilium/commit/1c84ae3b58a7cd54f7ee355e6c524c82f620eae8"
        },
        {
          "name": "https://github.com/cilium/cilium/commit/bacea640404c0805c23515353dc1681c5bf35171",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cilium/cilium/commit/bacea640404c0805c23515353dc1681c5bf35171"
        },
        {
          "name": "https://github.com/cilium/cilium/releases/tag/v1.19.5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/cilium/cilium/releases/tag/v1.19.5"
        }
      ],
      "source": {
        "advisory": "GHSA-fm8w-2m5w-9j7r",
        "discovery": "UNKNOWN"
      },
      "title": "Cilium may unexpectedly allow ingress traffic from the local namespace when a Kubernetes NetworkPolicy is configured with an ipBlock match"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-56743",
    "datePublished": "2026-07-15T19:15:30.924Z",
    "dateReserved": "2026-06-22T19:17:28.959Z",
    "dateUpdated": "2026-07-15T19:15:30.924Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-56743\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-07-15T20:17:51.987\",\"lastModified\":\"2026-07-15T20:54:43.733\",\"vulnStatus\":\"Undergoing Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Cilium is a networking, observability, and security solution. From 1.19.0 to 1.19.4, standard Kubernetes NetworkPolicy specifications using CIDR-based ipBlock rules without pod or namespace selectors erroneously generate a wildcard namespace allow rule when Cilium is configured with a custom clusterName rather than the default any value. The parser incorrectly instantiates a pod selector on selectorless peer definitions, allowing traffic from other workloads in the same namespace as the subject of the policy. This issue is fixed in version 1.19.5.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"cilium\",\"product\":\"cilium\",\"versions\":[{\"version\":\"\u003e= 1.19.0, \u003c 1.19.5\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N\",\"baseScore\":5.4,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"ADJACENT_NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"LOW\",\"integrityImpact\":\"LOW\",\"availabilityImpact\":\"NONE\"},\"exploitabilityScore\":2.3,\"impactScore\":2.7}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-863\"}]}],\"references\":[{\"url\":\"https://github.com/cilium/cilium/commit/1c84ae3b58a7cd54f7ee355e6c524c82f620eae8\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/cilium/cilium/commit/bacea640404c0805c23515353dc1681c5bf35171\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/cilium/cilium/pull/46305\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/cilium/cilium/pull/46456\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/cilium/cilium/releases/tag/v1.19.5\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/cilium/cilium/security/advisories/GHSA-fm8w-2m5w-9j7r\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}



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