CVE-2026-19033
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.
How to fix
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| ISC BIND 9 | 9.11.0 ≤ v ≤ 9.18.50, 9.20.0 ≤ v ≤ 9.20.27, 9.21.0 ≤ v ≤ 9.21.25, 9.11.3-S1 ≤ v ≤ 9.18.50-S1, 9.20.9-S1 ≤ v ≤ 9.20.27-S1 | — |
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