{"id":"AZL-44166","summary":"CVE-2021-31618 affecting package mod_http2 for versions less than 2.0.29-3","details":"Apache HTTP Server protocol handler for the HTTP/2 protocol checks received request headers against the size limitations as configured for the server and used for the HTTP/1 protocol as well. On violation of these restrictions and HTTP response is sent to the client with a status code indicating why the request was rejected. This rejection response was not fully initialised in the HTTP/2 protocol handler if the offending header was the very first one received or appeared in a a footer. This led to a NULL pointer dereference on initialised memory, crashing reliably the child process. Since such a triggering HTTP/2 request is easy to craft and submit, this can be exploited to DoS the server. This issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 only. Apache HTTP Server 2.4.47 was never released.","modified":"2026-04-01T05:15:29.731667Z","published":"2021-06-15T09:15:07Z","upstream":["CVE-2021-31618"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2021-31618"}],"affected":[{"package":{"name":"mod_http2","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/mod_http2"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.29-3"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-44166.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}