{"id":"CVE-2026-47778","summary":"Envoy: Embedded NUL in TLS DNS SAN Truncation in the Default TLS Certificate Validator. (Auth Bypass)","details":"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.","aliases":["BIT-envoy-2026-47778","GHSA-f8x4-rw5x-f3r7"],"modified":"2026-08-12T03:51:48.549921839Z","published":"2026-06-26T17:27:57.707Z","related":["openSUSE-SU-2026:11141-1"],"database_specific":{"cna_assigner":"GitHub_M","cwe_ids":["CWE-158"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47778.json"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/47xxx/CVE-2026-47778.json"},{"type":"ADVISORY","url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-f8x4-rw5x-f3r7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-47778"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/envoyproxy/envoy","events":[{"introduced":"0"},{"fixed":"adb998f2875986005be294d10231a9c9a497e30d"},{"introduced":"63ee0dc79dce88117c6bd2df5a742f8eb67ea980"},{"fixed":"57198c441a298a75097c690726d90974549a9778"},{"introduced":"6d9bb7d9a85d616b220d1f8fe67b61f82bbdb8d3"},{"fixed":"f97695a50e11f5ff6719e129a466bf9204b64a7f"},{"introduced":"f1dd21b16c244bda00edfb5ffce577e12d0d2ec2"},{"fixed":"0ebfcfe5b0484b89ca85b761da9e05ce75dbda8d"}],"database_specific":{"cpe":"cpe:2.3:a:envoyproxy:envoy:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"1.35.13"},{"introduced":"1.36.0"},{"fixed":"1.36.9"},{"introduced":"1.37.0"},{"fixed":"1.37.5"},{"introduced":"1.38.0"},{"fixed":"1.38.3"}],"source":"CPE_RANGE"}}],"versions":["v1.38.2","v1.37.4","v1.36.8","v1.35.12","v1.38.1","v1.37.3","v1.36.7","v1.35.11","v1.38.0","v1.37.2","v1.36.6","v1.35.10","v1.37.1","v1.36.5","v1.35.9","v1.37.0","v1.36.4","v1.35.8","v1.36.3","v1.35.7","v1.35.6","v1.36.2","v1.36.1","v1.35.5","v1.36.0","v1.35.4","v1.35.3","v1.35.2","v1.35.1","v1.35.0","v1.34.0","v1.33.0","v1.32.0","v1.31.0","v1.30.0","v1.29.0","v1.28.0","v1.27.0","v1.26.0","v1.25.0","v1.24.0","v1.23.0","v1.22.0","v1.21.0","v1.20.0","v1.19.0","v1.18.2","v1.18.1","v1.18.0","v1.17.0","v1.16.0","v1.15.0","v1.14.0","v1.13.0","v1.12.0","v1.11.0","v1.10.0","v1.9.0","v1.8.0","v1.7.0","v1.6.0","v1.5.0","v1.4.0","v1.3.0","v1.2.0","v1.1.0","v1.0.0"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-47778.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:N/A:N"}]}