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BIND 9 DNSSEC malformed DNSKEY CPU exhaustion DoS

IdentifiersCVE-2025-8677CWE-400

CVE-2025-8677 is a remote resource-exhaustion vulnerability in BIND 9 affecting DNSSEC validation on recursive resolvers. When a vulnerable resolver queries records in a specially crafted DNS zone containing certain malformed DNSKEY records, the resolver can enter excessive CPU-consuming processing, leading to resource exhaustion. The issue affects BIND 9 versions 9.18.0 through 9.18.39, 9.20.0 through 9.20.13, 9.21.0 through 9.21.12, 9.18.11-S1 through 9.18.39-S1, and 9.20.9-S1 through 9.20.13-S1. The available content attributes the flaw to malformed DNSKEY handling in BIND’s DNSSEC validation logic. Authoritative-only BIND servers are not affected.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation causes excessive CPU consumption on the affected BIND resolver, degrading or denying DNS resolution service for clients that depend on it. The practical impact is denial of service and loss of availability rather than integrity compromise or code execution. Recursive resolvers handling end-user queries are the primary exposure point.

Mitigation

If you can’t patch tonight, do this now.

No general workaround is available according to the provided ISC-related content. Where operationally feasible, reducing exposure by disabling recursion or ensuring the server is not used as a recursive DNSSEC-validating resolver can mitigate risk; authoritative-only deployments are not affected. Product-specific downstream guidance also notes disabling BIND entirely if not required. These measures may materially affect DNS service functionality, so the preferred mitigation is prompt upgrade to a fixed version.

Remediation

Patch, then assume compromise.

Upgrade BIND 9 to a fixed release. The content identifies patched versions as 9.18.41, 9.20.15, and 9.21.14, with Supported Preview Edition fixes in 9.18.41-S1 and 9.20.15-S1. Organizations on unsupported or discontinued branches should migrate to a supported fixed branch. No workaround is identified in the primary vulnerability content; patching is the required remediation.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
CanonicalJammy-Stemcell-Azureoperating_system
Internet Systems ConsortiumBindapplication
Rocky LinuxRocky Linuxoperating_system

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

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Social activity17

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