GitHub is removing SHA-1 RSA SSH signatures and a Diffie-Hellman key exchange, on a dated schedule
Four dates.4 From 14 October 2026, new RSA SSH keys must be at least 3072 bits, and the post-quantum mlkem768x25519-sha256 key exchange turns on. Brownouts of the ssh-rsa signature type and diffie-hellman-group-exchange-sha256 run on 4 November and 9 December. Removal is 13 January. Only Git-over-SSH clients are affected — if your remotes start with https://, none of this reaches you. Existing RSA keys do not need regenerating; they need a client that signs with rsa-sha2-256 or rsa-sha2-512, which most pick automatically.
Relevant to: Anyone whose CI, deploy keys or agent sandboxes speak Git over SSH from a pinned or old client image.
Minimum client versions GitHub names
OpenSSH 7.2p1 · JSch 0.1.66 (from GitHub's named fork) · TeamCity 2021.2.3 · Go SSH 0.16.0 · libssh2 1.11.0 · PuTTY 0.82.
GitHub's note distinguishes the key type ssh-rsa, which covers all RSA keys, from the signature type ssh-rsa, which means SHA-1 specifically. Only the signature type is being removed.
GitHub Enterprise Server picks the removals up in 3.25, and the ML-KEM addition in 3.24. The ML-KEM key exchange does not come to the U.S. region of GitHub Enterprise Cloud with Data Residency.4
One date in GitHub's own schedule reads "January 13, 2026", which is in the past; from the sequence it is plainly January 2027. We have not seen a correction on the page.