CVE-2023-28320 - siglongjmp race condition

How it was found

libcurl provides several different backends for resolving host names, selected at build time. If it is built to use the synchronous resolver, it allows name resolves to time-out slow operations using alarm() and siglongjmp().

When doing this, libcurl used a global buffer that was not mutex protected and a multi-threaded application might therefore crash or otherwise misbehave.

Impact

Denial of service due to a crash (likely) or possibly other impacts.