CVE-2026-2291

A heap buffer overflow was discovered in dnsmasq's DNS cache. When processing DNS responses, dnsmasq expands certain characters into longer escape sequences, but the cache buffer is not sized to hold the expanded result. A specially crafted DNS response can overflow this buffer, potentially crashing the dnsmasq process or poisoning DNS cache records.

Red Hat rates this issue as Moderate rather than Important. While DNS cache poisoning is possible, a process crash is the most likely outcome of a successful exploit. Also, standard upstream DNS resolvers reject the malformed responses before they reach dnsmasq, limiting exploitation to uncommon configurations where dnsmasq forwards directly to an attacker-controlled server.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.