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CVE-2026-19033

Unauthenticated IXFR deltas are applied to the live zone before TSIG verification

CVSS 3.1 6.5 MEDIUMCheck source for fixed versionsKEV status unknown

Original advisory

cve-program · CVE-2026-19033

Published

For a secondary zone with transfers restricted by TSIG, `named` may start to serve the data provided in a zone transfer before the final message with the TSIG signature arrives. This could allow an attacker that does not actually possess a valid TSIG signature to send unauthorized zone contents to a secondary server. Although no TSIG signature ever arrives, `named` does not rollback to the pre-transfer state. To exploit the vulnerability, the transfer must be a multi-message TCP IXFR, as described by RFC 8945. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.

Read the publisher's advisory

Affected versions, risk and source history

cve-program · CVE-2026-19033

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": "9.18.50",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.20.0",
                            "lessThanOrEqual": "9.20.27",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.21.0",
                            "lessThanOrEqual": "9.21.25",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.11.3-S1",
                            "lessThanOrEqual": "9.18.50-S1",
                            "status": "affected",
                            "versionType": "custom"
                        },
                        {
                            "version": "9.20.9-S1",
                            "lessThanOrEqual": "9.20.27-S1",
                            "status": "affected",
                            "versionType": "custom"
                        }
                    ],
                    "defaultStatus": "unaffected"
                }

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