---
id: CVE-2026-19033
title: >-
  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
summary: >-
  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…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L'
cwe:
  - CWE-349
  - CWE-347
vendor: ISC
product: BIND 9
affected:
  - bind_9 >= 9.11.0 <= 9.18.50
  - bind_9 >= 9.20.0 <= 9.20.27
  - bind_9 >= 9.21.0 <= 9.21.25
  - bind_9 >= 9.11.3-S1 <= 9.18.50-S1
  - bind_9 >= 9.20.9-S1 <= 9.20.27-S1
published: '2026-09-16'
updated: '2026-09-17'
sourceUpdated: '2026-09-17T18:16:38.860'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-19033'
references:
  - url: 'https://downloads.isc.org/isc/bind9/9.20.29'
    label: security-officer@isc.org
  - url: 'https://downloads.isc.org/isc/bind9/9.21.26'
    label: security-officer@isc.org
  - url: 'https://kb.isc.org/docs/cve-2026-19033'
    label: security-officer@isc.org
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-19033.json
  - url: 'https://access.redhat.com/security/cve/CVE-2026-19033'
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2535479'
  - url: 'https://www.cve.org/CVERecord?id=CVE-2026-19033'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-19033'
  - url: 'https://access.redhat.com/errata/RHSA-2026:68279'
tags:
  - nvd
  - cve.org
  - csaf
  - vex
  - red-hat
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-09-17T17:36:40.215995Z'
ingestedAt: '2026-09-16T14:57:28.063Z'
epss: 0.0024
epssPercentile: 0.13476
patched:
  - hardened_images
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Vendor advisories

- **Red Hat VEX** · Moderate · affected: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat OpenShift Container Platform 4 · no fix planned: Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, … · updated 2026-09-21 · [vex](https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-19033.json)
- **RHSA-2026:68279** · Red Hat · fixed in: Red Hat Hardened Images · released 2026-09-16 · [advisory](https://access.redhat.com/errata/RHSA-2026:68279)