{"id":"CVE-2023-43622","url":"https://www.cyber-defence.io/tools/cve/CVE-2023-43622","generatedAt":"2026-11-04T22:54:58.392Z","title":"An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server.","description":"An attacker, opening a HTTP/2 connection with an initial window size of 0, was able to block handling of that connection indefinitely in Apache HTTP Server. This could be used to exhaust worker resources in the server, similar to the well known \"slow loris\" attack pattern.\nThis has been fixed in version 2.4.58, so that such connection are terminated properly after the configured connection timeout.\n\nThis issue affects Apache HTTP Server: from 2.4.55 through 2.4.57.\n\nUsers are recommended to upgrade to version 2.4.58, which fixes the issue.","published":"2023-10-23T07:15:11.000Z","lastModified":"2026-06-17T06:26:05.000Z","status":"Modified","sourceIdentifier":"security@apache.org","cvss":{"version":"3.1","score":7.5,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},"cwe":["CWE-400"],"affected":["apache/http server"],"epss":{"score":0.68818,"percentile":0.99348,"date":"2026-11-03","history":[{"date":"2026-10-20","score":0.68818,"percentile":0.99344}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 68.8%, higher than 99% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"https://httpd.apache.org/security/vulnerabilities_24.html","tags":["Vendor Advisory"],"source":"security@apache.org"},{"url":"https://security.netapp.com/advisory/ntap-20231027-0011/","tags":["Third Party Advisory"],"source":"security@apache.org"},{"url":"https://httpd.apache.org/security/vulnerabilities_24.html","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://security.netapp.com/advisory/ntap-20231027-0011/","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2023-43622","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."}