CyberRota Analysis
AI-GeneratedUnbound versions 1.10.0 through 1.25.1 are vulnerable when the 'serve-expired: yes' option is enabled alongside specific response IP rules, allowing a remote attacker controlling a delegated domain to exploit a NULL pointer dereference. This can lead to a denial of service by crashing the daemon, particularly if the attacker can manipulate DNS responses within the configured response IP subnet. Organizations using affected versions of Unbound should prioritize patching to mitigate potential service disruptions.
Public Exploit Signal
A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.
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Original NVD Description
In NLnet Labs Unbound 1.10.0 up to and including 1.25.1, when 'serve-expired: yes' is set together with a 'response-ip: <net> redirect' /'response-ip-data: <net> CNAME <target>' rule (or the RPZ 'rpz-cname-override' equivalent), a remote client who controls any delegated domain can crash the daemon. The serve-expired-client-timeout callback runs a two-pass loop to chase the respip-generated CNAME alias; on the second pass it resets 'alias_rrset' but not 'partial_rep'. Later, this inconsistency leads to a NULL pointer dereference and an eventual crash. A malicious actor can exploit the vulnerability by controlling any zone that replies with an A/AAAA record that falls inside the configured response-ip/rpz subnet. By delaying the answer when the previous record has expired, the vulnerable path of 'serve-expired-client-timeout' is taken leading to denial of service via the server crash.
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