High severity · published Sep 16, 2026
CVE-2026-80225
Possible degradation of service from continuous queries on the same TCP/DoT connection
7.5
CVSS
0.5%
EPSS
No
On KEV
Description
In NLnetLabs Unbound up to and including 1.26.0, a degradation of service vulnerability is present in the TCP/DoT reading procedure where there is no limit on consecutive reads. A malicious actor that can stream and sustain a rate of distinct uncached names over the TCP/DoT connection, monopolizes a single worker's entire event loop for as long as its writes stay ahead of the drain.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 41% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UN
Unbound · NLnet Labs
before 1.26.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-80225
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-80225
Patch
https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-80225.txt
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