Unsafe media served inline on download endpoints in matrix-media-repo

Vulnerability Description

matrix-media-repo is a highly customizable multi-domain media repository for the Matrix chat ecosystem. In affected versions an attacker could upload a malicious piece of media to the media repo, which would then be served with `Content-Disposition: inline` upon download. This vulnerability could be leveraged to execute scripts embedded in SVG content. Commits `77ec235` and `bf8abdd` fix the issue and are included in the 1.3.0 release. Operators should upgrade to v1.3.0 as soon as possible. Operators unable to upgrade should override the `Content-Disposition` header returned by matrix-media-repo as a workaround.

References

• https://github.com/turt2live/matrix-media-repo/security/advisories/GHSA-5crw-6j7v-xc72
• https://github.com/turt2live/matrix-media-repo/commit/77ec2354e8f46d5ef149d1dcaf25f51c04149137
• https://github.com/turt2live/matrix-media-repo/commit/bf8abdd7a5371118e280c65a8e0ec2b2e9bdaf59
• https://developer.mozilla.org/en-US/docs/Web/SVG/Element/script