rustdesk-client RustDesk Client up to 1.4.5 src/client.Rs hash_password authentication replay

Summaryinfo

A vulnerability has been found in rustdesk-client RustDesk Client up to 1.4.5 and classified as critical. Affected is the function hash_password of the file src/client.Rs. The manipulation leads to authentication replay. This vulnerability is referenced as CVE-2026-30789. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability was found in rustdesk-client RustDesk Client up to 1.4.5 and classified as critical. This issue affects the function hash_password of the file src/client.Rs. The manipulation with an unknown input leads to a authentication replay vulnerability. Using CWE to declare the problem leads to CWE-294. A capture-replay flaw exists when the design of the product makes it possible for a malicious user to sniff network traffic and bypass authentication by replaying it to the server in question to the same effect as the original message (or with minor changes). Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Use of Password Hash With Insufficient Computational Effort, Improper Restriction of Excessive Authentication Attempts vulnerability in rustdesk-client RustDesk Client rustdesk-client on Windows, MacOS, Linux, iOS, Android (Client login, peer authentication modules) allows Password Brute Forcing. The authentication proof is SHA256(SHA256(password + salt) + challenge), where both the salt and the challenge are generated entirely by the server with no client-side nonce, and the hash uses no slow key-derivation function. A rogue or on-path API/relay server (see CVE-2026-30794 / CVE-2026-30797) can issue a chosen salt and challenge, capture the resulting proof, and recover the password offline. The capture-replay claim (CWE-294) is withdrawn: the challenge is regenerated per connection (challenge = Config::get_auto_password(6)), so a captured proof is not replayable against the legitimate server. The 1.4.7 OTP brute-force limiter and the existing LOGIN_FAILURES counter constrain only ONLINE attempts and do not address offline recovery. This vulnerability is associated with program files src/client.rs and program routines handle_hash(), handle_login_from_ui() (login proof construction). This issue affects RustDesk Client: through 1.4.8.

The weakness was published by Erez Kalman. The advisory is shared at rustdesk.com. The identification of this vulnerability is CVE-2026-30789 since 03/05/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/22/2026). MITRE ATT&CK project uses the attack technique T1040 for this issue.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Vendor

• rustdesk-client

Name

• RustDesk Client

Version

• 1.4.0
• 1.4.1
• 1.4.2
• 1.4.3
• 1.4.4
• 1.4.5

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