Threats Tagged 'cve-2026-40691'

Red Hat has issued a security advisory for Red Hat Hardened Images RPMs, specifically updating multiple unbound-related packages to version 1.25.2-0.1.hum1. This update addresses a high severity vulnerability identified as CVE-2026-40691. The advisory provides updated RPM packages for various architectures and includes bug fixes and enhancements. No explicit details about the nature of the vulnerability or exploitation are provided in the advisory. No known exploits in the wild have been reported at this time.

In Unbound 1.9.0 up to and including 1.25.1, when a DNSCrypt query is received over TCP, the routine that encrypts the reply in place fails to bound the reply length against the destination buffer size. The size clamp that protects the UDP path is not applied on the TCP path, so a reply larger than 65504 bytes is shifted forward by 48 bytes inside a buffer of capacity equal to 'msg-buffer-size', writing past the end of the heap allocation. A single malicious encrypted query crashes the resolver and lead to denial of service. This vulnerability needs Unbound to be compiled with DNSCrypt support ('--enable-dnscrypt') and the 'dnscrypt:' clause to be configured and enabled for the listening interfaces.