Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')

Summary

undici's setCookie function does not fully sanitize cookie attributes. In undici versions prior to 6.28.0, 7.0.0 prior to 7.29.0, and 8.0.0 prior to 8.9.0, a domain value is not checked for semicolons and entries in the unparsed array are not sanitized, so attacker-influenced input can inject additional cookie attributes. For example, a domain value containing a semicolon can append attributes such as SameSite, and an unparsed entry can inject attributes such as HttpOnly, without the caller setting them. Applications that pass user-controlled input to these fields, such as multi-tenant or reverse-proxy servers that scope session cookies to a tenant-supplied domain, can have SameSite CSRF protections bypassed, or the Secure, HttpOnly, and SameSite attributes forced, stripped, or overridden. The issue is fixed in undici 6.28.0, 7.29.0, and 8.9.0.