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CVE-2026-1519

Excessive NSEC3 iterations cause high CPU load during insecure delegation validation

CVSS 3.1 7.5 HIGHCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-1519

Published

If a BIND resolver is performing DNSSEC validation and encounters a maliciously crafted zone, the resolver may consume excessive CPU. Authoritative-only servers are generally unaffected, although there are circumstances where authoritative servers may make recursive queries (see: https://kb.isc.org/docs/why-does-my-authoritative-server-make-recursive-queries). This issue affects BIND 9 versions 9.11.0 through 9.16.50, 9.18.0 through 9.18.46, 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.46-S1, and 9.20.9-S1 through 9.20.20-S1.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-1519

Published

BIND 9

Vendor product

Publisher's version information

Shown as published. These rules are not interpreted as NuGet package version ranges.

{
                    "vendor": "ISC",
                    "product": "BIND 9",
                    "versions": [
                        {
                            "version": "9.11.0",
                            "lessThanOrEqual": "9.16.50",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.18.0",
                            "lessThanOrEqual": "9.18.46",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.20.0",
                            "lessThanOrEqual": "9.20.20",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.21.0",
                            "lessThanOrEqual": "9.21.19",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.11.3-S1",
                            "lessThanOrEqual": "9.16.50-S1",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.18.11-S1",
                            "lessThanOrEqual": "9.18.46-S1",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.20.9-S1",
                            "lessThanOrEqual": "9.20.20-S1",
                            "status": "affected",
                            "versionType": "custom"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

Original source record · Cite this exact observation · Complete original publisher JSON