Vulnerability RUSTSEC-2026-0487

When an SVCB or HTTPS record is parsed from its text (zone file) form, the alpn service parameter value is split into a list of protocol names. That step called expect on the result, on the assumption that it could not fail. A malformed value, such as one with an unbalanced quote (alpn="h), two commas in a row or an invalid escape, makes it fail, so the parser panicked instead of returning an error.

Code that parses zone files or record text from an untrusted source can be made to panic, which is a denial of service. Records decoded from the DNS wire format are not parsed this way.

The fix returns a parse error instead. It is in 0.26.2.