{"id":"CVE-2021-23351","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-23351","generatedAt":"2026-10-27T22:34:00.111Z","title":"The package github.com/pires/go-proxyproto before 0.5.0 are vulnerable to Denial of Service (DoS) via the parseVersion1() function.","description":"The package github.com/pires/go-proxyproto before 0.5.0 are vulnerable to Denial of Service (DoS) via the parseVersion1() function. The reader in this package is a default bufio.Reader wrapping a net.Conn. It will read from the connection until it finds a newline. Since no limits are implemented in the code, a deliberately malformed V1 header could be used to exhaust memory in a server process using this code - and create a DoS. This can be exploited by sending a stream starting with PROXY and continuing to send data (which does not contain a newline) until the target stops acknowledging. The risk here is small, because only trusted sources should be allowed to send proxy protocol headers.","published":"2021-03-08T05:15:13.000Z","lastModified":"2026-06-17T03:38:36.000Z","status":"Modified","sourceIdentifier":"report@snyk.io","cvss":{"version":"3.1","score":4.9,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H"},"cwe":[],"affected":["go-proxyproto project/go-proxyproto","fedoraproject/fedora"],"epss":{"score":0.01871,"percentile":0.79211,"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":"low","text":"Lower severity and a low EPSS score (1.87%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://github.com/pires/go-proxyproto/commit/7f48261db810703d173f27f3309a808cc2b49b8b","tags":["Patch","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://github.com/pires/go-proxyproto/issues/69","tags":["Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://github.com/pires/go-proxyproto/pull/71","tags":["Patch","Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4BNVGJMVI3ZTZ675EFPUHPGXCKCGSX46/","source":"report@snyk.io"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/C36IBVOZXRTWM7MGTRUTOM56P5RR74VU/","source":"report@snyk.io"},{"url":"https://snyk.io/vuln/SNYK-GOLANG-GITHUBCOMPIRESGOPROXYPROTO-1081577","tags":["Third Party Advisory"],"source":"report@snyk.io"},{"url":"https://github.com/pires/go-proxyproto/commit/7f48261db810703d173f27f3309a808cc2b49b8b","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/pires/go-proxyproto/issues/69","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://github.com/pires/go-proxyproto/pull/71","tags":["Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4BNVGJMVI3ZTZ675EFPUHPGXCKCGSX46/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/C36IBVOZXRTWM7MGTRUTOM56P5RR74VU/","source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://snyk.io/vuln/SNYK-GOLANG-GITHUBCOMPIRESGOPROXYPROTO-1081577","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-23351","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."}