{"id":"CVE-2019-18801","url":"https://www.cyber-defence.io/tools/cve/CVE-2019-18801","generatedAt":"2026-10-27T21:18:37.105Z","title":"An untrusted remote client may send HTTP/2 requests that write to the heap outside of the request buffers when the upstream is HTTP/1.","description":"An issue was discovered in Envoy 1.12.0. An untrusted remote client may send HTTP/2 requests that write to the heap outside of the request buffers when the upstream is HTTP/1. This may be used to corrupt nearby heap contents (leading to a query-of-death scenario) or may be used to bypass Envoy's access control mechanisms such as path based routing. An attacker can also modify requests from other users that happen to be proximal temporally and spatially.","published":"2019-12-13T13:15:11.000Z","lastModified":"2026-06-17T02:25:22.000Z","status":"Modified","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":9.8,"severity":"CRITICAL","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-787"],"affected":["envoyproxy/envoy"],"epss":{"score":0.02502,"percentile":0.84604,"date":"2026-10-26","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 (2.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://access.redhat.com/errata/RHSA-2019:4222","tags":["Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://blog.envoyproxy.io","tags":["Product"],"source":"cve@mitre.org"},{"url":"https://github.com/envoyproxy/envoy/commits/master","tags":["Patch"],"source":"cve@mitre.org"},{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-gxvv-x4p2-rppp","tags":["Exploit","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://groups.google.com/forum/#%21forum/envoy-users","source":"cve@mitre.org"},{"url":"https://access.redhat.com/errata/RHSA-2019:4222","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://blog.envoyproxy.io","tags":["Product"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/envoyproxy/envoy/commits/master","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/envoyproxy/envoy/security/advisories/GHSA-gxvv-x4p2-rppp","tags":["Exploit","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://groups.google.com/forum/#%21forum/envoy-users","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2019-18801","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."}