Medium (4.3). EPSS 1.1% chance of exploitation in the next 30 days. Fixed in stdlib 1.21.8, 1.22.1.
When following an HTTP redirect to a domain which is not a subdomain match or exact match of the initial domain, an http.Client does not forward sensitive headers such as "Authorization" or "Cookie". For example, a redirect from foo.com to www.foo.com will forward the Authorization header, but a redirect to bar.com will not. A maliciously crafted HTTP redirect could cause sensitive headers to be unexpectedly forwarded.
Severity
CVSS 3.1
4.3 medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
EPSS
1.1% chance of exploitation in the next 30 days; higher than 65% of CVEs (scores of 2026-10-31)