{"id":"CVE-2021-28662","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-28662","generatedAt":"2026-10-27T22:33:42.538Z","title":"If a remote server sends a certain response header over HTTP or HTTPS, there is a denial of service.","description":"An issue was discovered in Squid 4.x before 4.15 and 5.x before 5.0.6. If a remote server sends a certain response header over HTTP or HTTPS, there is a denial of service. This header can plausibly occur in benign network traffic.","published":"2021-05-27T12:15:08.000Z","lastModified":"2026-06-17T03:46:44.000Z","status":"Modified","sourceIdentifier":"cve@mitre.org","cvss":{"version":"3.1","score":6.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H"},"cwe":["CWE-116"],"affected":["squid-cache/squid","debian/debian linux","fedoraproject/fedora"],"epss":{"score":0.7176,"percentile":0.9942,"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":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 71.8%, higher than 99% of all known CVEs. Patch or mitigate before the next change window."},"changes":[],"references":[{"url":"http://seclists.org/fulldisclosure/2023/Oct/14","tags":["Mailing List","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"http://www.openwall.com/lists/oss-security/2023/10/11/3","tags":["Mailing List","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"http://www.squid-cache.org/Versions/v6/changesets/squid-6-051824924c709bd6162a378f746fb859454c674e.patch","tags":["Patch","Vendor Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/squid-cache/squid/commit/051824924c709bd6162a378f746fb859454c674e","tags":["Patch","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://github.com/squid-cache/squid/security/advisories/GHSA-jjq6-mh2h-g39h","tags":["Patch","Third Party Advisory"],"source":"cve@mitre.org"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/","source":"cve@mitre.org"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/","source":"cve@mitre.org"},{"url":"https://www.debian.org/security/2021/dsa-4924","tags":["Third Party Advisory"],"source":"cve@mitre.org"},{"url":"http://seclists.org/fulldisclosure/2023/Oct/14","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.openwall.com/lists/oss-security/2023/10/11/3","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"http://www.squid-cache.org/Versions/v6/changesets/squid-6-051824924c709bd6162a378f746fb859454c674e.patch","tags":["Patch","Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/squid-cache/squid/commit/051824924c709bd6162a378f746fb859454c674e","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/squid-cache/squid/security/advisories/GHSA-jjq6-mh2h-g39h","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/LSQ3U54ZCNXR44QRPW3AV2VCS6K3TKCF/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/T4EPIWUZDJAXADDHVOPKRBTQHPBR6H66/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://www.debian.org/security/2021/dsa-4924","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-28662","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."}