enable the proposed repo (and pin it to a lower priority) and install the package explicitly

https://ubuntu.com/project/docs/SRU/reference/sru-verificati...

or download the individual package (and dpkg --install ... but this doesn't check signatures)

https://ubuntu.pkgs.org/26.04/ubuntu-proposed-main-amd64/lin...

check https://ubuntu.com/security/CVE-2026-98432