CVE-2026-19401High· 7.5▾ TwilightAny remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the …
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 41.3 · likelihood 0.1 · exploitation 0
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Exploit-prediction probability, daily snapshots since Sep 8.
Disclosure to exploitation, from the record and what we observed since indexing it.
Disclosed via NVD
Last analysed / modified upstream
0.3%
0.3% → 0.4%
Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.
nsd >= 4.3.7, < 4.15.1Upgrade past the affected range:
nsd 4.15.1Connected by shared product, vendor, weakness, or advisory.
CVE-2026-18664Critical· 9.1When ranges are used for access control (i.e
CVE-2026-18916High· 7.5Any remote client can crash a NSD serve child, by throttling the TCP receive window after a TCP query
CVE-2026-19538High· 7.5The BLOCKED access control list items that are evaluated to deny access on the the proxy protocol port can be bypassed completely when connecting over TCP or TLS and sending the query twice on connection that is kept open.
CVE-2025-69534High· 7.5Python-Markdown version 3.8 contain a vulnerability where malformed HTML-like sequences can cause html.parser.HTMLParser to raise an unhandled AssertionError during Markdown parsing
CVE-2020-3563High· 8.6A vulnerability in the packet processing functionality of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device
CVE-2020-3554High· 7.5A vulnerability in the TCP packet processing of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) conditi…