RUSTSEC-2026-0099: Name constraints were accepted for certificates asserting a wildcard name

> Name constraints were accepted for certificates asserting a wildcard name

| Details | |
| ------------------- | ---------------------------------------------- |
| Package | `rustls-webpki` |
| Version | `0.103.8` |
| Date | 2026-04-14 |
| Patched versions | `>=0.103.12, <0.104.0-alpha.1,>=0.104.0-alpha.6` |

Permitted subtree name constraints for DNS names were accepted for certificates asserting a wildcard name.

This was incorrect because, given a name constraint of `accept.example.com`, `*.example.com` could feasibly allow a name of `reject.example.com` which is outside the constraint.
This is very similar to [CVE-2025-61727](https://go.dev/issue/76442).

Since name constraints are restrictions on otherwise properly-issued certificates, this bug is reachable only after signature verification and requires misissuance to exploit.

This vulnerability is identified as [GHSA-xgp8-3hg3-c2mh](https://github.com/rustls/webpki/security/advisories/GHSA-xgp8-3hg3-c2mh). Thank you to @1seal for the report.

See [advisory page](https://rustsec.org/advisories/RUSTSEC-2026-0099.html) for additional details.

Review the repository's Rust dependency declarations to see whether rustls-webpki 0.103.8 is present; no file or test is named in the issue. Done means the affected dependency is no longer on 0.103.8 and the project's existing checks pass.

Written by the indexing model from the issue text.