CVE-2020-25682: debian debian_linux Heap-based Buffer Overflow

Vulnerability summary

CVE-2020-25682 is a high (CVSS 8.3) Heap-based Buffer Overflow vulnerability in debian debian_linux. EPSS estimates a 70.75% chance of exploitation in the next 30 days, higher than 99.3% of scored vulnerabilities.

Timeline

1. 20-01-2021
   PublishedVulnerability first disclosed.
2. 04-11-2025
   Last modifiedVulnerability information updated.

Description

A flaw was found in dnsmasq before 2.83. A buffer overflow vulnerability was discovered in the way dnsmasq extract names from DNS packets before validating them with DNSSEC data. An attacker on the network, who can create valid DNS replies, could use this flaw to cause an overflow with arbitrary data in a heap-allocated memory, possibly executing code on the machine. The flaw is in the rfc1035.c:extract_name() function, which writes data to the memory pointed by name assuming MAXDNAME*2 bytes are available in the buffer. However, in some code execution paths, it is possible extract_name() gets passed an offset from the base buffer, thus reducing, in practice, the number of available bytes that can be written in the buffer. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
• CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.