An issue was discovered 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.
Weakness
The product dereferences a pointer that it expects to be valid but is NULL.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Atftp | Atftp_project | 0.7.1 (including) | 0.7.1 (including) |
| Atftp | Ubuntu | bionic | * |
| Atftp | Ubuntu | cosmic | * |
| Atftp | Ubuntu | disco | * |
| Atftp | Ubuntu | esm-apps/bionic | * |
| Atftp | Ubuntu | esm-apps/xenial | * |
| Atftp | Ubuntu | trusty | * |
| Atftp | Ubuntu | xenial | * |
Potential Mitigations
References
- 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
- 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