{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "1.37.0"
              },
              {
                "fixed": "1.37.1"
              }
            ]
          },
          "events": [
            {
              "introduced": "6d9bb7d9a85d616b220d1f8fe67b61f82bbdb8d3"
            },
            {
              "fixed": "5ef4e4cea57f63e7e2970b9c1ad696278db927d6"
            }
          ],
          "repo": "https://github.com/envoyproxy/envoy",
          "type": "GIT"
        },
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "1.36.0"
              },
              {
                "fixed": "1.36.5"
              }
            ]
          },
          "events": [
            {
              "introduced": "63ee0dc79dce88117c6bd2df5a742f8eb67ea980"
            },
            {
              "fixed": "41749943780b54b70b510b1b1a4805ae529e174a"
            }
          ],
          "repo": "https://github.com/envoyproxy/envoy",
          "type": "GIT"
        },
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "1.35.0"
              },
              {
                "fixed": "1.35.9"
              }
            ]
          },
          "events": [
            {
              "introduced": "84305a6cb64bd55aaf606bdd53de7cd6080427a1"
            },
            {
              "fixed": "75e220883447543d35571aecae826d7b1a2646b9"
            }
          ],
          "repo": "https://github.com/envoyproxy/envoy",
          "type": "GIT"
        },
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.34.13"
              }
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7c0fda3dc457de6ee4585e8129e3f5728d65f367"
            }
          ],
          "repo": "https://github.com/envoyproxy/envoy",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-56cj-wgg3-x943"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-193"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26309.json"
  },
  "details": "Envoy is a high-performance edge/middle/service proxy. Prior to 1.37.1, 1.36.5, 1.35.8, and 1.34.13, an off-by-one write in Envoy::JsonEscaper::escapeString() can corrupt std::string null-termination, causing undefined behavior and potentially leading to crashes or out-of-bounds reads when the resulting string is later treated as a C-string. This vulnerability is fixed in 1.37.1, 1.36.5, 1.35.8, and 1.34.13.",
  "id": "CVE-2026-26309",
  "modified": "2026-03-13T13:49:59.239493729Z",
  "published": "2026-03-10T19:04:21.384Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26309.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/envoyproxy/envoy/security/advisories/GHSA-56cj-wgg3-x943"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26309"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Envoy has an off-by-one write in JsonEscaper::escapeString()"
}