Description
Russh is a Rust SSH client & server library. Prior to 0.62.4, an unauthenticated SSH client can cause a denial of service by sending SSH_MSG_KEX_ECDH_INIT with a 32-byte all-zero Q_C value. Curve25519Kex::server_dh in russh/src/kex/curve25519.rs accepts the all-zero peer public value and computes an all-zero shared secret, after which compute_exchange_hash calls encode_mpint in russh/src/kex/mod.rs and indexes beyond the end of the input while skipping leading zero bytes. The resulting panic occurs before authentication and terminates the server key-exchange task. This issue is fixed in version 0.62.4.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Eugeny | russh | < 0.62.4 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | rust-russh | 0.64.1-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | rust-russh | No fix yet | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | yazi | 26.5.6-r7 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| crates.io | russh | < 0.62.4 | 0.62.4 | GHSA-5xvq-cp9x-6p6r |