CVE-2020-25683: Buffer Overflow
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. A remote attacker, who can create valid DNS replies, could use this flaw to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extractname(), which could be abused to make the code execute memcpy() with a negative size in getrdata() and cause a crash in dnsmasq, resulting in a denial of service. The highest threat from this vulnerability is to system availability.
Other sources
An heap-based buffer overflow was discovered in dnsmasq when DNSSEC is enabled and before it validates the received DNS entries. A remote attacker, who can create valid DNS replies, could use this flaw to cause an overflow in a heap-allocated memory. This flaw is caused by the lack of length checks in rfc1035.c:extractname(), which could be abused to make the code execute memcpy() with a negative size in getrdata() and cause a crash in dnsmasq.
— Red Hat
Affected Software
Remediation
Patch Available
Event History
Frequently Asked Questions
What is CVE-2020-25683?
CVE-2020-25683 is a vulnerability found in dnsmasq before version 2.83 that allows a remote attacker to cause a heap-based buffer overflow.
How does CVE-2020-25683 affect dnsmasq?
CVE-2020-25683 affects dnsmasq when DNSSEC is enabled and before it validates the received DNS entries.
Who is affected by CVE-2020-25683?
Users of dnsmasq versions before 2.83 are affected by CVE-2020-25683.
What is the severity of CVE-2020-25683?
The severity of CVE-2020-25683 is high with a CVSS score of 5.9.
How can I mitigate CVE-2020-25683?
To mitigate CVE-2020-25683, update dnsmasq to version 2.83 or later.