Git file transport

See repro.sh.

cd super
git submodule add ../sub

This results in:

fatal: transport 'file' not allowed

This is a new limitation which seems to have come about as a result of a patch related to security.

Workaround

git -c protocol.file.allow=always submodule add ../sub

Sources

• https://bugs.launchpad.net/ubuntu/+source/git/+bug/1993586
  • Mentions the git -c protocol.file.allow=always submodule add … workaround
• https://github.blog/2022-10-18-git-security-vulnerabilities-announced/#cve-2022-39253
  • GitHub blog announcing the Git CVE fixes including this one
  • Links to the source of the security advisory which I've added below
• https://github.com/git/git/security/advisories/GHSA-3wp6-j8xr-qw85
  • The security advisory
• https://git-scm.com/docs/git-config#Documentation/git-config.txt-protocolallow
  • The Git setting for protocol.file.allow
  • Wasn't clear to me this needs to go between git and submodule