CVE-2020-25681 Memory corruption in dnsmasq

What is CVE-2020-25681?

CVE-2020-25681 is a high-severity memory corruption vulnerability in Debian Debian Linux, published on 20 Jan 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

A flaw was found in dnsmasq before version 2.83. A heap-based buffer overflow was discovered in the way RRSets are sorted before validating with DNSSEC data. An attacker on the network, who can forge DNS replies such as that they are accepted as valid, could use this flaw to cause a buffer overflow with arbitrary data in a heap memory segment, possibly executing code on the machine. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.

Weakness: CWE-122

Which versions are affected by CVE-2020-25681?

It affects 3 products.

Products include Debian Debian Linux, Fedoraproject Fedora, Thekelleys Dnsmasq.

How do I fix CVE-2020-25681?

Upgrade to a fixed version.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2020-25681 being exploited?

There is no known exploitation of CVE-2020-25681 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

• CVE-2015-3306 ProFTPD Improper Access Control Exploited Critical 10.0
• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as ALPINE-CVE-2020-25681, CLEANSTART-2026-DX67539, DEBIAN-CVE-2020-25681, GHSA-34v3-rp23-947c, UBUNTU-CVE-2020-25681.