CVE-2026-47778 (GCVE-0-2026-47778)

Vulnerability from cvelistv5 – Published: 2026-06-26 17:27 – Updated: 2026-06-27 02:53
VLAI?
Title
Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass)
Summary
Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a structural flaw was identified in DefaultCertValidator::verifySubjectAltName where the extracted DNS SAN string is cast to a C-style string using .c_str() before being passed to the Utility::dnsNameMatch() algorithm. If the attacker serves a certificate with a dNSName SAN containing an embedded NUL byte, the helper Utility::generalNameAsString captures the complete string including the NUL. However, when .c_str() evaluates it, implicit conversion to absl::string_view inside dnsNameMatch relies on strlen(), prematurely truncating the evaluation context. Envoy evaluates trucated string against the exact required config_san match and returns true, thereby successfully validating the string with the Nul byte for an upstream routing. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.
Severity ?
4.4 (Medium)
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N
CWE
  • CWE-158 - Improper Neutralization of Null Byte or NUL Character
Assigner
References
Impacted products
Vendor Product Version
envoyproxy envoy Affected: >= 1.38.0, < 1.38.1
Affected: >= 1.37.0, < 1.37.3
Affected: >= 1.36.0, < 1.36.7
Affected: < 1.35.11
Create a notification for this product.
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-47778",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-06-27T02:52:00.418621Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-06-27T02:53:13.826Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-f8x4-rw5x-f3r7"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "envoy",
          "vendor": "envoyproxy",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 1.38.0, \u003c 1.38.1"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.37.0, \u003c 1.37.3"
            },
            {
              "status": "affected",
              "version": "\u003e= 1.36.0, \u003c 1.36.7"
            },
            {
              "status": "affected",
              "version": "\u003c 1.35.11"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a structural flaw was identified in DefaultCertValidator::verifySubjectAltName where the extracted DNS SAN string is cast to a C-style string using .c_str() before being passed to the Utility::dnsNameMatch() algorithm. If the attacker serves a certificate with a dNSName SAN containing an embedded NUL byte, the helper Utility::generalNameAsString captures the complete string including the NUL. However, when .c_str() evaluates it, implicit conversion to absl::string_view inside dnsNameMatch relies on strlen(), prematurely truncating the evaluation context. Envoy evaluates trucated string against the exact required config_san match and returns true, thereby successfully validating the string with the Nul byte for an upstream routing. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 4.4,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "HIGH",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-158",
              "description": "CWE-158: Improper Neutralization of Null Byte or NUL Character",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-06-26T17:27:57.707Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-f8x4-rw5x-f3r7",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-f8x4-rw5x-f3r7"
        }
      ],
      "source": {
        "advisory": "GHSA-f8x4-rw5x-f3r7",
        "discovery": "UNKNOWN"
      },
      "title": "Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-47778",
    "datePublished": "2026-06-26T17:27:57.707Z",
    "dateReserved": "2026-05-19T22:36:16.883Z",
    "dateUpdated": "2026-06-27T02:53:13.826Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-47778\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"poc\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-06-27T02:52:00.418621Z\"}}}], \"references\": [{\"url\": \"https://github.com/envoyproxy/envoy/security/advisories/GHSA-f8x4-rw5x-f3r7\", \"tags\": [\"exploit\"]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-06-27T02:53:05.767Z\"}}], \"cna\": {\"title\": \"Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass)\", \"source\": {\"advisory\": \"GHSA-f8x4-rw5x-f3r7\", \"discovery\": \"UNKNOWN\"}, \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 4.4, \"attackVector\": \"NETWORK\", \"baseSeverity\": \"MEDIUM\", \"vectorString\": \"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N\", \"integrityImpact\": \"NONE\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"HIGH\", \"availabilityImpact\": \"NONE\", \"privilegesRequired\": \"HIGH\", \"confidentialityImpact\": \"HIGH\"}}], \"affected\": [{\"vendor\": \"envoyproxy\", \"product\": \"envoy\", \"versions\": [{\"status\": \"affected\", \"version\": \"\u003e= 1.38.0, \u003c 1.38.1\"}, {\"status\": \"affected\", \"version\": \"\u003e= 1.37.0, \u003c 1.37.3\"}, {\"status\": \"affected\", \"version\": \"\u003e= 1.36.0, \u003c 1.36.7\"}, {\"status\": \"affected\", \"version\": \"\u003c 1.35.11\"}]}], \"references\": [{\"url\": \"https://github.com/envoyproxy/envoy/security/advisories/GHSA-f8x4-rw5x-f3r7\", \"name\": \"https://github.com/envoyproxy/envoy/security/advisories/GHSA-f8x4-rw5x-f3r7\", \"tags\": [\"x_refsource_CONFIRM\"]}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to 1.35.11, 1.36.7, 1.37.3, and 1.38.1, a structural flaw was identified in DefaultCertValidator::verifySubjectAltName where the extracted DNS SAN string is cast to a C-style string using .c_str() before being passed to the Utility::dnsNameMatch() algorithm. If the attacker serves a certificate with a dNSName SAN containing an embedded NUL byte, the helper Utility::generalNameAsString captures the complete string including the NUL. However, when .c_str() evaluates it, implicit conversion to absl::string_view inside dnsNameMatch relies on strlen(), prematurely truncating the evaluation context. Envoy evaluates trucated string against the exact required config_san match and returns true, thereby successfully validating the string with the Nul byte for an upstream routing. This vulnerability is fixed in 1.35.11, 1.36.7, 1.37.3, and 1.38.1.\"}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-158\", \"description\": \"CWE-158: Improper Neutralization of Null Byte or NUL Character\"}]}], \"providerMetadata\": {\"orgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"shortName\": \"GitHub_M\", \"dateUpdated\": \"2026-06-26T17:27:57.707Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-47778\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-06-27T02:53:13.826Z\", \"dateReserved\": \"2026-05-19T22:36:16.883Z\", \"assignerOrgId\": \"a0819718-46f1-4df5-94e2-005712e83aaa\", \"datePublished\": \"2026-06-26T17:27:57.707Z\", \"assignerShortName\": \"GitHub_M\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




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.