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Vulnerability · Published Sep 16, 2026 · Assigned by isc

CVE-2026-19033Unauthenticated IXFR deltas are applied to the live zone before TSIG verification

Medium 6.5

In plain English

A medium-severity security flaw in BIND 9 from ISC. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.2% (higher than 15% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.5Medium
Exploit odds (30 days)0.2%top 84.8% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Alpine:v3.22bind9.20.29-r0ALPINE-CVE-2026-19033
Alpine:v3.23bind9.20.29-r0ALPINE-CVE-2026-19033
Alpine:v3.24bind9.20.29-r0ALPINE-CVE-2026-19033
Debian:12bind91:9.18.49-1~deb12u3DEBIAN-CVE-2026-19033
Debian:13bind91:9.20.29-1~deb13u1DEBIAN-CVE-2026-19033
Debian:14bind91:9.20.29-1DEBIAN-CVE-2026-19033
Ubuntu:22.04:LTSbind91:9.18.39-0ubuntu0.22.04.8USN-8969-1
Ubuntu:22.04:LTSbind91:9.18.39-0ubuntu0.22.04.7USN-8929-1
Ubuntu:22.04:LTSbind91:9.18.39-0ubuntu0.22.04.7UBUNTU-CVE-2026-19033
Ubuntu:24.04:LTSbind91:9.18.39-0ubuntu0.24.04.9USN-8969-1
Ubuntu:24.04:LTSbind91:9.18.39-0ubuntu0.24.04.8UBUNTU-CVE-2026-19033
Ubuntu:24.04:LTSbind91:9.18.39-0ubuntu0.24.04.8USN-8929-1
Ubuntu:26.04:LTSbind91:9.20.24-1ubuntu0.4USN-8929-1
Ubuntu:26.04:LTSbind91:9.20.24-1ubuntu0.5USN-8969-1
Ubuntu:26.04:LTSbind91:9.20.24-1ubuntu0.4UBUNTU-CVE-2026-19033
Ubuntu:26.10bind91:9.20.24-1ubuntu3.1UBUNTU-CVE-2026-19033
Ubuntu:26.10bind91:9.20.24-1ubuntu3.1USN-8969-1
Ubuntu:22.04:LTSbind9-libsno fix listedUBUNTU-CVE-2026-19033
Ubuntu:24.04:LTSisc-dhcpno fix listedUBUNTU-CVE-2026-19033
Ubuntu:26.04:LTSisc-dhcpno fix listedUBUNTU-CVE-2026-19033

Affected products (as reported)

VendorProductVersions
ISC BIND 9 9.11.0 – through 9.18.509.20.0 – through 9.20.279.21.0 – through 9.21.259.11.3-S1 – through 9.18.50-S19.20.9-S1 – through 9.20.27-S1

Weakness: CWE-349 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L

References