# CVE-2026-11622 — ISC BIND 9

> As of 2026-07-22, CVE-2026-11622 is a HIGH-severity vulnerability in ISC BIND 9, CVSS v3.1 7.5, EPSS 0.5% (43.3th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-11622, most recently “F5 BIG-IP DNS Denial of Service via BIND DNSSEC Random Subdomain Attack (CVE-2026-11622)”.

**Last updated:** 2026-07-22

## What is CVE-2026-11622?

A DNSSEC validating resolver that is under a random subdomain attack against a DNSSEC-signed zone can suffer from runaway memory usage. The attacker needs to be able to send queries faster than the resolver can perform validation. The increased memory usage can be orders of magnitude beyond the limit configured in the `max-cache-size` parameter. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.24-S1.

The record classifies CVE-2026-11622 under weakness class [CWE-770](https://cwe.mitre.org/data/definitions/770.html). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 61 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.5 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **EPSS (FIRST):** 0.5% probability of exploitation in the next 30 days, higher than 43.3% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-22

## Is CVE-2026-11622 being exploited?

No public exploitation evidence for CVE-2026-11622 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-07-22. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.

## Affected products and versions

- **ISC**: BIND 9

## How to fix CVE-2026-11622

No vendor patch reference has been recorded for CVE-2026-11622 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-11622

1 tracked threat in the Threadlinqs corpus references CVE-2026-11622, either in the campaign’s CVE list or as an indicator on the campaign record.

- [F5 BIG-IP DNS Denial of Service via BIND DNSSEC Random Subdomain Attack (CVE-2026-11622)](https://intel.threadlinqs.com/threat/TL-2026-2596) — HIGH · 2026-09-21

## Sources

Enriched from CVE.org, NVD, FIRST EPSS. Last verified by Threadlinqs on 2026-09-21. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [kb.isc.org — vendor advisory](https://kb.isc.org/docs/cve-2026-11622)
- [downloads.isc.org — patch](https://downloads.isc.org/isc/bind9/9.20.26)
- [downloads.isc.org — patch (9.21)](https://downloads.isc.org/isc/bind9/9.21.24)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-11622
Full detection coverage and IOCs for threats exploiting CVE-2026-11622 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp