A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. This flaw allows a remote attacker, who can create valid DNS replies, to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extract_name(), which could be abused to make the code execute memcpy() with a negative size in sort_rrset() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.
Source: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-25687
Reference (s):
- DEBIAN:DSA-4844
- URL: https://www.debian.org/security/2021/dsa-4844
- FEDORA:FEDORA-2021-2e4c3d5a9d
- URL: https://lists.fedoraproject.org/archives/list/[email protected]/message/QGB7HL3OWHTLEPSMLDGOMXQKG3KM2QME/
- FEDORA:FEDORA-2021-84440e87ba