---
id: "CVE-2026-19630"
kind: "vulnerability"
aliases: ["CVE-2026-19630"]
title: "BIND: crafted DNS messages make the resolver burn CPU and memory"
severity: "high"
cvss: 7.5
epss: 0.00448
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["bind", "dns", "infrastructure", "linux", "self-hosted"]
not_affected_if: ["authoritative-only", "recursion-restricted", "version-outside-range"]
published_at: "2026-10-21T13:18:32+00:00"
first_seen_at: "2026-10-23T21:57:28+00:00"
updated_at: "2026-10-25T03:16:52+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-19630", "first_seen_at": "2026-10-23T21:57:28+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-19630", "first_seen_at": "2026-10-24T13:15:54+00:00"}]
---

# BIND: crafted DNS messages make the resolver burn CPU and memory

A crafted inbound DNS message with a very large number of a specific record structure makes a BIND resolver do unbounded extra processing. An attacker can exhaust CPU and memory on the resolver, causing slowdown or denial of service.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `named -V` or `named -v` to read the BIND version and compare it with the affected ranges.
- Check whether the host runs BIND as a recursive resolver (`recursion yes;` in named.conf) that accepts queries from untrusted networks.

## Fix

- Upgrade BIND 9 branches past the affected ranges: move past `9.18.50`, `9.20.29`, `9.21.26`, `9.18.50-S1` and `9.20.29-S1` to a fixed release from ISC.
- Restrict recursive queries to trusted clients with `allow-recursion` until patched.

## Timeline

- 2026-10-23T21:57:28+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-19630
- 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-19630

## From the sources

In a BIND resolver, inbound DNS protocol messages with a particular structure will result in additional processing, with no limit imposed by BIND.  A DNS message with a maliciously large number of such structures will cause BIND to consume disproportionate amounts of CPU time and memory during processing.
This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_