DNS cache poisoning via unsigned wildcard proofs
Published Jul 23, 2026 · Updated Jul 23, 2026
DNSSEC validation bypass in PowerDNS Recursor allows remote attackers to poison cached DNS answers through crafted wildcard replies. In syncres.cc, wildcard expansion logic accepts the NSEC or NSEC3 proof without validating its signature when the wildcard answer is a CNAME or DNAME record. Exploitation requires a crafted reply from an authoritative server under narrowly constrained conditions outside the attacker's control; the bounded consequence is cache poisoning without system compromise.
Summary
What happened
DNSSEC validation bypass in PowerDNS Recursor allows remote attackers to poison cached DNS answers through crafted wildcard replies. In syncres.cc, wildcard expansion logic accepts the NSEC or NSEC3 proof without validating its signature when the wildcard answer is a CNAME or DNAME record. Exploitation requires a crafted reply from an authoritative server under narrowly constrained conditions outside the attacker's control; the bounded consequence is cache poisoning without system compromise.
The record
- CVE
- CVE-2026-52686
- Published
- Jul 23, 2026
- Updated
- Jul 23, 2026
- Vendor
- PowerDNS
- Product
- PowerDNS Recursor
- Classifications
- CWE-345, CWE-347, CAPEC-142, T1565.002
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jul 23, 2026CVE publishedPublication date reported by the CVE source.
- Jul 23, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.2.0 <5.2.12
- Affected versionversion=5.3.0 <5.3.9
- Affected versionversion=5.4.0 <5.4.4
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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