At work, I've seen some cases where people provide "C" in the Accept-Language header of their Git requests, such as when they provide us with debugging traces, but "C" and "POSIX", while valid locales, are not valid languages and do not belong in the Accept-Language header. It turns out this is actually very easy to reproduce and fix, so there's a patch to filter these out. I have not actually myself seen "POSIX" in the header, but it's equivalent to "C" and I've seen it in non-Git requests in various places online, so we reject that as well. This can be seen in GitLab's issues as well at https://gitlab.com/gitlab-org/gitlab/-/issues/412077. brian m. carlson (1): http: don't send C or POSIX in Accept-Language http.c | 8 ++++++++ t/t5541-http-push-smart.sh | 18 ++++++++++++++++++ 2 files changed, 26 insertions(+)