High [CVE-2026-19667] Denial of Service via 16-bit length truncation in DNS negative cache handling
This high-severity Red Hat Linux advisory covers CVE-2026-19667; related products: Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 10.
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Summary
Denial of Service via 16-bit length truncation in DNS negative cache handling. Red Hat rates this important (CVSS 7.5).
Weakness: CWE-190. Red Hat lists fixing advisory RHSA-2026:75577 with package bind9.18-32:9.18.29-14.el9_8.10, bind-main-9.20.29-0.1.hum1, bind-32:9.18.33-15.el10_2.12, bind-32:9.16.23-40.el9_8.10.
Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 10.
- 9.11.0
- 9.18.50
- 9.20.0
- 9.20.27
- 9.21.0
- 9.21.25
- 9.11.3
- 9.20.9
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
- bind9.18-32:9.18.29-14.el9_8.10
- bind-main-9.20.29-0.1.hum1
- bind-32:9.18.33-15.el10_2.12
- bind-32:9.16.23-40.el9_8.10
- RHSA-2026:75577
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Mitigation checklist
- To reduce the exposure to this vulnerability, configure BIND 9 to forward all DNS queries to trusted, non-vulnerable upstream DNS servers. This prevents the local `named` instance from directly interacting with potentially malicious authoritative servers. Example configuration in `named.conf`: ``` options { forwarders { 192.0.2.1; 192.0.2.2; }; forward only; }; ``` Replace `192.0.2.1` and `192.0.2.2` with the IP addresses of your trusted upstream DNS servers. After modifying the configuration, restart the `named` service for the changes to take effect. This configuration may impact DNS resolution if the configured forwarders are unavailable or do not provide comprehensive resolution.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
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