Bug 2380930 (CVE-2025-40776)

Summary: CVE-2025-40776 bind: Birthday Attack against Resolvers supporting ECS
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: high Docs Contact:
Priority: high    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the `named` caching resolver, a component of BIND 9. When this resolver is configured to send EDNS Client Subnet (ECS) options, it may be vulnerable to a cache-poisoning attack. A remote attacker could exploit this to compromise the integrity of cached DNS data. This could lead to users being redirected to malicious websites or services. EDNS Client Subnet (ECS) options are only available in the BIND Subscription Edition (-S), so only the -S edition is affected by this CVE.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2025-07-16 14:01:52 UTC
A `named` caching resolver that is configured to send ECS (EDNS Client Subnet) options may be vulnerable to a cache-poisoning attack.
This issue affects BIND 9 versions 9.11.3-S1 through 9.16.50-S1, 9.18.11-S1 through 9.18.37-S1, and 9.20.9-S1 through 9.20.10-S1.