#VU47133 NULL pointer dereference in atftp - CVE-2019-11366

Vulnerability identifier: #VU47133

Vulnerability risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-11366

CWE-ID: CWE-476

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
atftp
Web applications / Modules and components for CMS

Vendor: Dennis Kaarsemaker

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to a NULL pointer dereference error in atftpd in atftp 0.7.1. It does not lock the thread_list_mutex mutex before assigning the current thread data structure. As a result, the daemon is vulnerable to a denial of service attack due to a NULL pointer dereference. If thread_data is NULL when assigned to current, and modified by another thread before a certain tftpd_list.c check, there is a crash when dereferencing current->next. A remote attacker can perform a denial of service (DoS) attack.

Mitigation
Cybersecurity Help is currently unaware of any official solution to address this vulnerability.

Vulnerable software versions

atftp: 0.7.1

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External links
https://lists.debian.org/debian-lts-announce/2019/05/msg00012.html
https://pulsesecurity.co.nz/advisories/atftpd-multiple-vulnerabilities
https://seclists.org/bugtraq/2019/May/16
https://security.gentoo.org/glsa/202003-14
https://sourceforge.net/p/atftp/code/ci/382f76a90b44f81fec00e2f609a94def4a5d3580/
https://usn.ubuntu.com/4540-1/
https://www.debian.org/security/2019/dsa-4438

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.