CVE-2021-23351: Fedoraproject Fedora

Medium severity, CVSS 4.9. EPSS: 1.9% chance of exploitation in the next 30 days.

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.

Affected products

• Fedoraproject Fedora: version 33 only; version 34 only
• Go-Proxyproto Project Go-Proxyproto: before 0.5.0 (fixed in 0.5.0)

Published 2021-03-08. Last modified 2026-06-17.