Sources: National Vulnerability Database, CVE.org, CISA KEV, FIRST EPSS
CVE-2026-123576 Overview
Hickory DNS 0.24.0 through 0.26.1 contains a memory exhaustion vulnerability that allows remote attackers to consume server resources by sending incomplete DNS-over-QUIC request bodies. Attackers can open many connections and send only large length prefixes, causing pre-allocated buffers to persist without timeout and exhausting server memory.
Critical Impact
Affected Products
- Hickory DNS: see the vendor advisory for the exact affected versions
Discovery Timeline
- 2026-11-08: CVE-2026-123576 published to the National Vulnerability Database by disclosure@vulncheck.com
- 2026-11-08: last updated in the NVD database
Technical Details for CVE-2026-123576
Vulnerability Analysis
CVE-2026-123576 is a Allocation Without Limits weakness (CWE-770: Allocation Without Limits) in Hickory DNS. Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Resources are allocated without a cap.
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-770: Allocation Without Limits. Resources are allocated without a cap.
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-2026-123576
Detection Strategies
- Inventory every instance of Hickory DNS 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 Hickory DNS 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-2026-123576
Immediate Actions Required
- Apply the fixed version of Hickory DNS 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 Hickory DNS.
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-770: Allocation Without Limits 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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