{"id":"CVE-2023-27493","url":"https://www.cyber-defence.io/tools/cve/CVE-2023-27493","generatedAt":"2026-10-25T17:57:53.202Z","title":"In the worst case, it can cause upstream service to interpret the original request as two pipelined requests, possibly bypassing the intent of Envoy’s security policy.","description":"Envoy is an open source edge and service proxy designed for cloud-native applications. Prior to versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9, Envoy does not sanitize or escape request properties when generating request headers. This can lead to characters that are illegal in header values to be sent to the upstream service. In the worst case, it can cause upstream service to interpret the original request as two pipelined requests, possibly bypassing the intent of Envoy’s security policy. Versions 1.26.0, 1.25.3, 1.24.4, 1.23.6, and 1.22.9 contain a patch. As a workaround, disable adding request headers based on the downstream request properties, such as downstream certificate properties.","published":"2023-04-04T20:15:07.000Z","lastModified":"2026-06-17T05:45:20.000Z","status":"Modified","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"3.1","score":9.1,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N"},"cwe":["CWE-20","CWE-444"],"affected":["envoyproxy/envoy"],"epss":{"score":0.00507,"percentile":0.42462,"date":"2026-10-24","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.51%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-w5w5-487h-qv8q","tags":["Exploit","Vendor Advisory"],"source":"security-advisories@github.com"},{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-w5w5-487h-qv8q","tags":["Exploit","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2023-27493","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}