Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-123570 Overview
The DNS wire-format message parser in hickory-proto (Hickory DNS) 0.18 before 0.26.2 preallocates record vectors sized by the untrusted ANCOUNT, NSCOUNT, and ARCOUNT header fields before reading record data. Remote attackers can send a UDP datagram, or a spoofed response to a client/resolver, with these counts set to 65535, forcing about 18MB of allocation per message.
Critical Impact
Affected Products
- Product named in vendor advisory: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-08: CVE-2026-123570 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-08: last updated in the NVD database
Technical Details for CVE-2026-123570
Vulnerability Analysis
CVE-2026-123570 is a Uncontrolled Resource Consumption weakness (CWE-400: Uncontrolled Resource Consumption) in Product named in vendor advisory. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. An attacker can exhaust CPU, memory or connections.
With a CVSS base score of 8.7, apply the vendor fix and confirm exposure on internet facing and business critical assets first.
Root Cause
The weakness is classified as CWE-400: Uncontrolled Resource Consumption. An attacker can exhaust CPU, memory or connections.
Attack Vector
Based on the CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Attack complexity is low complexity.
No exploitation in the wild is confirmed by CISA at the time of the last update. Check the references below for any vendor or researcher proof of concept.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Detection Methods for CVE-2026-123570
Detection Strategies
- Inventory every instance of Product named in vendor advisory and compare the running version with the affected range above.
- Check external attack surface scans for internet facing instances of the component.
- Run an authenticated vulnerability scan once your scanner ships a check for this CVE.
Monitoring Recommendations
- Forward Product named in vendor advisory application, access and audit logs to your SIEM for retrospective hunting.
- Alert on new processes, configuration changes or outbound connections from the affected service.
- Track the vendor advisory and the CISA KEV catalog for changes in exploitation status.
How to Mitigate CVE-2026-123570
Immediate Actions Required
- Apply the fixed version of Product named in vendor advisory named in the vendor advisory.
- Prioritize internet facing and business critical instances first.
- Rescan after the change to confirm the exposure is closed.
Patch Information
Use the fixed version listed in the vendor advisory for Product named in vendor advisory.
Workarounds
- If patching must wait, restrict network access to the affected service and place it behind authentication or a web application firewall rule.
CWE References
- CWE-400: Uncontrolled Resource Consumption More CVEs with this weakness
Technical References
This entry is built directly from NVD, CISA KEV and EPSS data. Verify fixed versions in the vendor advisory before you deploy.
Frequently asked questions
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