CVE-2026-19033
Unauthenticated IXFR deltas are applied to the live zone before TSIG verification
- State
- Published
- Severity
- 6.5 Medium
- Published
- Sep 16, 2026
- Updated
- Sep 17, 2026
- Reserved
- Aug 6, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.5 Medium | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:L | isc |
Weaknesses
- CWE-349 Acceptance of Extraneous Untrusted Data With Trusted Data
Affected Products
| Product | Versions |
|---|---|
BIND 9ISC |
|
References
- CVE-2026-19033vendor-advisory
- https://downloads.isc.org/isc/bind9/9.20.29patch
- https://downloads.isc.org/isc/bind9/9.21.26patch
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