{"id":"CVE-2026-26309","aliases":["BIT-envoy-2026-26309","GHSA-56cj-wgg3-x943"],"url":"https://o3.security/vulnerability/CVE-2026-26309","summary":"Envoy has an off-by-one write in JsonEscaper::escapeString()","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.","published":"2026-03-10T19:04:21.384Z","modified":"2026-08-07T11:31:17.925919770Z","cvss":{"score":5.3,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"},"epss":null,"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/envoyproxy/envoy","fixedVersion":null},{"ecosystem":"Go","name":"github.com/envoyproxy/envoy","fixedVersion":null},{"ecosystem":"Go","name":"github.com/envoyproxy/envoy","fixedVersion":null},{"ecosystem":"Go","name":"github.com/envoyproxy/envoy","fixedVersion":null}],"fix":null,"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"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:31:17.925919770Z"}}