EUVD-2026-326678

fkie_cve-2026-48110

Russh is a Rust SSH client & server library. From version 0.34.0 to before version 0.61.0, several russh client and server message handlers decoded attacker-controlled SSH strings, name-lists, and byte fields into owned allocations before applying field-specific bounds. A remote SSH peer could send oversized, high-fanout, or malformed length-prefixed fields and make the library allocate, attempt to allocate, or split data before rejecting input that should have been rejected earlier. This issue has been patched in version 0.61.0.

GHSA-4r3c-5hpg-58qr — Russh SSH message fields were decoded through allocation-first parsers before field-specific bounds

Affected: crates.io: russh

# SSH message fields were decoded through allocation-first parsers before field-specific bounds

### Summary

Several `russh` client and server message handlers decoded attacker-controlled SSH strings, name-lists, and byte fields into owned allocations before applying field-specific bounds. A remote SSH peer could send oversized, high-fanout, or malformed length-prefixed fields and make the library allocate, attempt to allocate, or split data before rejecting input that should have been rejected earlier.

### Affected Versions

Oldest verified exploitable stable release: `russh 0.34.0`.

- Historical stronger case: `russh >= 0.34.0, < 0.58.0`. These releases have the allocation-first KEXINIT field parsing issue and still use `CryptoVec` for inbound packet/decompression buffers. A peer can combine negotiated RFC `zlib`, rekey, compressed KEXINIT expansion, historical `CryptoVec` decompression growth, and KEXINIT name-list fanout. - Current maintained-line case: `russh >= 0.58.0`, including `0.60.2`. These releases moved non-secret packet/decompression buffers off `CryptoVec`, but the allocation-first SSH field parser issue remains reachable as a `Vec`/`String`/name-list resource exhaustion issue.

Prerelease coverage was not claimed for the zlib/`CryptoVec`/KEXINIT combo because the combined historical exploit shape was verified against stable `v0.34.0`-era code and reproduced the stress behavior on `v0.57.1`.

### Details

The affected parser pattern appeared across the SS…

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EUVD-2026-326678

fkie_cve-2026-48110

GHSA-4r3c-5hpg-58qr — Russh SSH message fields were decoded through allocation-first parsers before field-specific bounds