CVE-2026-55717 Detail
Received
This CVE record has recently been published to the CVE List and has been included within the NVD dataset. DescriptionIn 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. Metrics
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CVSS 4.0 Severity and Vector Strings:
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Weakness Enumeration
Quick InfoCVE Dictionary Entry:CVE-2026-55717 NVD Published Date: 07/22/2026 NVD Last Modified: 07/22/2026 Source: NLnet Labs |
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