GHSA-5v8h-3h3q-446p: Nokogiri: Possible Use-After-Free when `Nokogiri::XML::Document#encoding=` raises an exception

Calling Document#encoding= with an invalid encoding (e.g., a non-string, or a string containing a null byte) raises an exception, but only after freeing the document’s current encoding string without replacing it. The document is left referencing freed memory, so the next call to Document#encoding reads invalid memory, which can cause a segfault or leak freed bytes into a Ruby String.

Affects the CRuby (libxml2) implementation only; JRuby is not affected.