{"id":"CVE-2023-35944","aliases":["BIT-envoy-2023-35944","EUVD-2023-39928","GHSA-pvgm-7jpg-pw5g"],"status":"published","title":"Envoy vulnerable to incorrect handling of HTTP requests and responses with mixed case schemes","description":"Envoy is an open source edge and service proxy designed for cloud-native applications. Envoy allows mixed-case schemes in HTTP/2, however, some internal scheme checks are case-sensitive. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, this can lead to the rejection of requests with mixed-case schemes such as `htTp` or `htTps`, or the bypassing of some requests such as `https` in unencrypted connections. With a fix in versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, Envoy will now lowercase scheme values by default, and change the internal scheme checks that were case-sensitive to be case-insensitive. There are no known workarounds for this issue.","severity":{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00704,"percentile":0.53594,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-20","CWE-444"],"published":"2023-07-25T18:35:59Z","modified":"2026-10-28T02:30:27Z","fixes":[{"ecosystem":"Bitnami","package":"envoy","fixed_in":["1.23.12","1.24.10","1.25.9","1.26.4"],"sources":["osv"]}],"affected":[{"source":"osv","ecosystem":"Bitnami","package":"envoy","ranges":[{"type":"SEMVER","events":[{"introduced":"1.23.0"},{"fixed":"1.23.12"},{"introduced":"1.24.0"},{"fixed":"1.24.10"},{"introduced":"1.25.0"},{"fixed":"1.25.9"},{"introduced":"1.26.0"},{"fixed":"1.26.4"}]}]}],"products":[{"vendor":"envoyproxy","product":"envoy"}],"references":[{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-pvgm-7jpg-pw5g","tags":["x_refsource_CONFIRM","x_transferred","Exploit","Third Party Advisory","advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2023-35944","tags":["web","advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2023/35xxx/CVE-2023-35944.json","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2023-35944","title":"Envoy vulnerable to incorrect handling of HTTP requests and responses with mixed case schemes","description":"Envoy is an open source edge and service proxy designed for cloud-native applications. Envoy allows mixed-case schemes in HTTP/2, however, some internal scheme checks are case-sensitive. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, this can lead to the rejection of requests with mixed-case schemes such as `htTp` or `htTps`, or the bypassing of some requests such as `https` in unencrypted connections. With a fix in versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, Envoy will now lowercase scheme values by default, and change the internal scheme checks that were case-sensitive to be case-insensitive. There are no known workarounds for this issue.","status":"published","published":"2023-07-25T18:35:59.135Z","modified":"2024-10-23T20:18:42.493Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high","assessor":"cna"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T14:35:33.794347Z"}],"euvd":[{"id":"EUVD-2023-39928","description":"Envoy is an open source edge and service proxy designed for cloud-native applications. Envoy allows mixed-case schemes in HTTP/2, however, some internal scheme checks are case-sensitive. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, this can lead to the rejection of requests with mixed-case schemes such as `htTp` or `htTps`, or the bypassing of some requests such as `https` in unencrypted connections. With a fix in versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, Envoy will now lowercase scheme values by default, and change the internal scheme checks that were case-sensitive to be case-insensitive. There are no known workarounds for this issue.","status":"published","published":"2023-07-25T18:35:59Z","modified":"2024-10-23T20:18:42Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"updated_at":"2026-11-03T00:05:20.595169Z"}],"nvd":[{"id":"CVE-2023-35944","description":"Envoy is an open source edge and service proxy designed for cloud-native applications. Envoy allows mixed-case schemes in HTTP/2, however, some internal scheme checks are case-sensitive. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, this can lead to the rejection of requests with mixed-case schemes such as `htTp` or `htTps`, or the bypassing of some requests such as `https` in unencrypted connections. With a fix in versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, Envoy will now lowercase scheme values by default, and change the internal scheme checks that were case-sensitive to be case-insensitive. There are no known workarounds for this issue.","status":"published","published":"2023-07-25T19:15:11.24Z","modified":"2026-06-17T06:05:31.26Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-20","CWE-444"],"updated_at":"2026-11-02T14:08:18.687088Z"}],"osv":[{"id":"CVE-2023-35944","title":"Envoy vulnerable to incorrect handling of HTTP requests and responses with mixed case schemes","description":"Envoy is an open source edge and service proxy designed for cloud-native applications. Envoy allows mixed-case schemes in HTTP/2, however, some internal scheme checks are case-sensitive. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, this can lead to the rejection of requests with mixed-case schemes such as `htTp` or `htTps`, or the bypassing of some requests such as `https` in unencrypted connections. With a fix in versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, Envoy will now lowercase scheme values by default, and change the internal scheme checks that were case-sensitive to be case-insensitive. There are no known workarounds for this issue.","status":"published","published":"2023-07-25T18:35:59.135Z","modified":"2026-10-28T02:30:27.676321255Z","cvss":[{"version":"3.1","score":8.2,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N","level":"high"}],"cwes":["CWE-20"],"updated_at":"2026-11-02T15:44:32.510144Z"},{"id":"BIT-envoy-2023-35944","title":"Envoy vulnerable to incorrect handling of HTTP requests and responses with mixed case schemes","description":"Envoy is an open source edge and service proxy designed for cloud-native applications. Envoy allows mixed-case schemes in HTTP/2, however, some internal scheme checks are case-sensitive. Prior to versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, this can lead to the rejection of requests with mixed-case schemes such as `htTp` or `htTps`, or the bypassing of some requests such as `https` in unencrypted connections. With a fix in versions 1.27.0, 1.26.4, 1.25.9, 1.24.10, and 1.23.12, Envoy will now lowercase scheme values by default, and change the internal scheme checks that were case-sensitive to be case-insensitive. There are no known workarounds for this issue.","status":"published","published":"2024-03-06T10:52:47.709Z","modified":"2026-09-10T16:01:31.644641162Z","updated_at":"2026-11-02T15:28:29.563843Z"}]}}