In ProFTPD 1.3.7, it is possible to corrupt the memory pool by interrupting the data transfer channel. This triggers a use-after-free in alloc_pool in pool.c, and possible remote code execution.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-9273
• proftpd/proftpd#903
• https://cert-portal.siemens.com/productcert/pdf/ssa-679335.pdf
• https://github.com/proftpd/proftpd/blob/master/RELEASE_NOTES
• https://lists.debian.org/debian-lts-announce/2020/02/msg00022.html
• https://lists.debian.org/debian-lts-announce/2020/03/msg00002.html
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VCUPRYSJR7XOM3HQ6H5M4OGDU7OHCHBF/
• https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XHO3S5WPRRP7VGKIAHLYQVEYW5HRYIJN/
• https://security.gentoo.org/glsa/202003-35
• https://www.debian.org/security/2020/dsa-4635
• http://lists.opensuse.org/opensuse-security-announce/2020-03/msg00002.html
• http://www.openwall.com/lists/oss-security/2021/08/25/1
• http://www.openwall.com/lists/oss-security/2021/09/06/2