What’s Vulnerable › Vulnerabilities

CVE-2026-11605: Unnecessary validation of DNSSEC signed records

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-22 · updated 2026-10-24
• Weakness: CWE-408

Description

The issue is a resource exhaustion vulnerability associated with DNSSEC validation. BIND always validates all RRSIG records in an answer, even if they are not strictly needed. A query to an authoritative server/zone which returns many valid but superfluous RRSIG records causes the validator to waste disproportionate CPU time. This issue affects BIND 9 versions 9.20.0 through 9.20.24, 9.21.0 through 9.21.23, and 9.20.9-S1 through 9.20.24-S1.

Affected products

• ISC BIND: from 9.20.0 through 9.20.24; from 9.21.0 through 9.21.23; from 9.20.9-S1 through 9.20.24-S1

References

• https://downloads.isc.org/isc/bind9/9.20.26
• https://downloads.isc.org/isc/bind9/9.21.24
• https://kb.isc.org/docs/cve-2026-11605

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