AIKIDO-2026-335387
russh is vulnerable to Denial of Service (DoS)
37
Low Risk
This Affects:
russhTL;DR
russh allows a block cipher that requires message authentication, such as AES-CBC, AES-CTR, or 3DES-CBC, to be negotiated together with mac=none, because the MAC-selection logic only checks cipher and MAC pairing when negotiation would otherwise fail. With no MAC in place, a peer can send a packet whose decrypted length field is zero, shrinking the input buffer below already-buffered data and triggering a slice index panic. This crashes the affected SSH connection. The fix rejects or substitutes mac=none whenever the chosen cipher needs a MAC and guards against buffer shrinkage below consumed bytes.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range and a connection negotiates a MAC-requiring block cipher (such as AES-CBC, AES-CTR, or 3DES-CBC) together with mac=none, which lets an untrusted peer send a crafted packet that panics the connection task.
Background info
russh is vulnerable to Denial of Service (DoS) in versions 0.0.1 - 0.63.0.
How to fix this
Upgrade the russh library to the patch version.
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SOC 2Compliant
ISO 27001Compliant