Client session crash via malformed X25519 reply
Published Aug 12, 2026 · Updated Aug 12, 2026
Denial of service in Eugeny russh before 0.62.4 allows remote attackers to crash a client session via a malformed SSH key-exchange reply. Curve25519Kex::compute_shared_secret copies an unchecked, attacker-sized server ephemeral value into a fixed 32-byte buffer, causing clone_from_slice to panic. Exploitation requires a russh client to connect to a malicious or man-in-the-middle SSH server; the panic normally ends only the spawned session task.
Summary
What happened
Denial of service in Eugeny russh before 0.62.4 allows remote attackers to crash a client session via a malformed SSH key-exchange reply. Curve25519Kex::compute_shared_secret copies an unchecked, attacker-sized server ephemeral value into a fixed 32-byte buffer, causing clone_from_slice to panic. Exploitation requires a russh client to connect to a malicious or man-in-the-middle SSH server; the panic normally ends only the spawned session task.
The record
- CVE
- CVE-2026-73429
- Published
- Aug 12, 2026
- Updated
- Aug 12, 2026
- Vendor
- Russh Project
- Product
- russh
- Classifications
- CWE-754, CWE-704, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 12, 2026CVE publishedPublication date reported by the CVE source.
- Aug 12, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.62.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Standalone Cargo wrong-length X25519 reply PoCproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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