#VU97707 Input validation error in ZNC - CVE-2024-39844

Vulnerability identifier: #VU97707

Vulnerability risk: High

CVSSv4.0: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Amber]

CVE-ID: CVE-2024-39844

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
ZNC
Server applications / IDS/IPS systems, Firewalls and proxy servers

Vendor: ZNC

Description

The vulnerability allows a remote user to compromise the affected system.

The vulnerability exists due to insufficient validation of user-supplied input in modtcl  when processing the reason to kick a user from the channel. A remote user can pass specially crafted input to the application and execute arbitrary code on the server.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

ZNC: 1.6.1 rc1 - 1.9.0

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External links
https://wiki.znc.in/Category:ChangeLog
https://github.com/znc/znc/releases/tag/znc-1.9.1
https://wiki.znc.in/ChangeLog/1.9.1
https://www.openwall.com/lists/oss-security/2024/07/03/9
https://www.openwall.com/lists/oss-security/2024/07/03/9

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.