{"cve":"CVE-2021-23351","nvd":{"published":"2021-03-08T05:15:12.593","modified":"2026-06-17T03:38:36.220","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","score":4.9},"cwes":[],"references":["https://github.com/pires/go-proxyproto/commit/7f48261db810703d173f27f3309a808cc2b49b8b","https://github.com/pires/go-proxyproto/issues/69","https://github.com/pires/go-proxyproto/pull/71","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4BNVGJMVI3ZTZ675EFPUHPGXCKCGSX46/","https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/C36IBVOZXRTWM7MGTRUTOM56P5RR74VU/"],"products":["fedoraproject:fedora","go-proxyproto_project:go-proxyproto"],"source":"nvd","synced_at":"2026-10-19T21:15:50.279857260+00:00"},"epss":{"cve":"CVE-2021-23351","score":0.01871,"percentile":0.79362,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-fqh4-rh59-xhvf","url":"https://osv.dev/vulnerability/GHSA-fqh4-rh59-xhvf","summary":"github.com/pires/go-proxyproto denial of service vulnerability","modified":"2026-07-08T06:49:45.606596500Z","packages":[{"ecosystem":"Go","name":"github.com/pires/go-proxyproto","purl":"pkg:golang/github.com/pires/go-proxyproto","ranges":["<0.5.0"],"fixed":["0.5.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}