LetsEncrypt announced its new "Generation Y" root hierarchy on
2025-11-24 and switched its default ACME profile to issue from the new
roots in May 2026. Our baked-in fallback root store only contained the
Generation X roots (ISRG Root X1 and X2), so chains terminating at the
new ISRG Root YE (ECDSA P-384) or ISRG Root YR (RSA 4096) roots failed
to verify when the system roots were also missing them.
Add both new self-signed roots, fetched from
https://letsencrypt.org/certificates/ (valid 2025-09-03 to 2045-09-02).
Also add a live network test, run by default in CI only (or with
--run-live-lets-encrypt-test), that verifies the baked-in roots alone
are sufficient to validate LetsEncrypt's per-root test endpoints for
X1, X2, YE, and YR.
Fixes#20527
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: Ic69076d8ae5aae08db167095745e92c53357afe3
Brad FitzpatrickandBrad Fitzpatrick
f65372c9ba