CVE-2026-73429: CWE-704: Incorrect Type Conversion or Cast in Eugeny russh
CVE-2026-73429 is a medium severity vulnerability in the russh Rust SSH client & server library. Versions prior to 0.62.4 are affected by an incorrect type conversion issue where a malformed KEX_ECDH_REPLY message from a malicious SSH server can cause the client to panic and terminate the session task. This occurs because the client does not validate the length of a server ephemeral value before cloning it, leading to a deterministic panic. The embedding process remains running despite the session termination. The issue is fixed in version 0.62.4.
AI Analysis
Technical Summary
Russh is a Rust SSH client and server library. In versions before 0.62.4, a malicious SSH server can send a malformed KEX_ECDH_REPLY message containing a server ephemeral value that is not 32 bytes long. The client-side function Curve25519Kex::compute_shared_secret in russh/src/kex/curve25519.rs calls clone_from_slice on this value without validating its length, causing a deterministic panic. This panic terminates the spawned client session task and surfaces as a JoinError, but the embedding process remains running. This vulnerability is classified under CWE-704 (Incorrect Type Conversion or Cast) and CWE-754 (Improper Check for Unusual or Exceptional Conditions). The issue is resolved in russh version 0.62.4.
Potential Impact
An attacker controlling an SSH server can cause a russh client session to crash by sending a malformed key exchange reply with an incorrectly sized ephemeral value. This results in a deterministic panic that terminates the client session task, causing a denial of service for that session. The overall embedding process remains operational, so the impact is limited to session disruption without further compromise of confidentiality or integrity.
Mitigation Recommendations
Upgrade russh to version 0.62.4 or later, where this issue is fixed by validating the length of the server ephemeral value before processing. No other mitigations are indicated.
CVE-2026-73429: CWE-704: Incorrect Type Conversion or Cast in Eugeny russh
Description
CVE-2026-73429 is a medium severity vulnerability in the russh Rust SSH client & server library. Versions prior to 0.62.4 are affected by an incorrect type conversion issue where a malformed KEX_ECDH_REPLY message from a malicious SSH server can cause the client to panic and terminate the session task. This occurs because the client does not validate the length of a server ephemeral value before cloning it, leading to a deterministic panic. The embedding process remains running despite the session termination. The issue is fixed in version 0.62.4.
CVSS v3.1
Score 5.3medium
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Russh is a Rust SSH client and server library. In versions before 0.62.4, a malicious SSH server can send a malformed KEX_ECDH_REPLY message containing a server ephemeral value that is not 32 bytes long. The client-side function Curve25519Kex::compute_shared_secret in russh/src/kex/curve25519.rs calls clone_from_slice on this value without validating its length, causing a deterministic panic. This panic terminates the spawned client session task and surfaces as a JoinError, but the embedding process remains running. This vulnerability is classified under CWE-704 (Incorrect Type Conversion or Cast) and CWE-754 (Improper Check for Unusual or Exceptional Conditions). The issue is resolved in russh version 0.62.4.
Potential Impact
An attacker controlling an SSH server can cause a russh client session to crash by sending a malformed key exchange reply with an incorrectly sized ephemeral value. This results in a deterministic panic that terminates the client session task, causing a denial of service for that session. The overall embedding process remains operational, so the impact is limited to session disruption without further compromise of confidentiality or integrity.
Mitigation Recommendations
Upgrade russh to version 0.62.4 or later, where this issue is fixed by validating the length of the server ephemeral value before processing. No other mitigations are indicated.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-12T14:32:11.796Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a7ce1eabf8831d5392b034b
Added to database: 08/12/2026, 21:13:14 UTC
Last enriched: 08/12/2026, 21:28:03 UTC
Last updated: 08/13/2026, 01:33:16 UTC
Views: 6
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