It looks like libexpat is in trouble, and needs help from experienced C developers: https://github.com/libexpat/libexpat/blob/R_2_6_2/expat/Changes#L8-L31

What you can do:
- If you're an experienced C developer, and can commit to helping maintain it, reach out to them. I expect that they're mainly looking for long-term collaborators, not just one-off contributions.
- If not, pass it on to people you know who might be able and interested to help out.

(Note that I'm not in contact with them - I'm just passing on the message!)