CVE-2026-52684Network attack vector

Persistent cache poisoning via uncapped refresh TTLs

Published Jul 23, 2026 · Updated Jul 23, 2026

Cache poisoning in PowerDNS Recursor before 5.5.0 allows remote attackers controlling an authoritative server to persist false DNS data. During refresh-almost-expired processing, the packet and record caches fail to cap TTLs when a slow authoritative response arrives after child records expire. The nondefault refresh-on-ttl-perc feature and nearly expired authoritative NS records are required, allowing poisoned answers to persist beyond intended TTLs.

CVSS severity3.7
Low
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cache poisoning in PowerDNS Recursor before 5.5.0 allows remote attackers controlling an authoritative server to persist false DNS data. During refresh-almost-expired processing, the packet and record caches fail to cap TTLs when a slow authoritative response arrives after child records expire. The nondefault refresh-on-ttl-perc feature and nearly expired authoritative NS records are required, allowing poisoned answers to persist beyond intended TTLs.

The record

CVE
CVE-2026-52684
Published
Jul 23, 2026
Updated
Jul 23, 2026
Vendor
PowerDNS
Product
PowerDNS Recursor
Classifications
Unavailable
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 23, 2026CVE publishedPublication date reported by the CVE source.
  2. 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.

  1. Affected versionversion=0.0.0 <5.5.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

PowerDNS · PowerDNS Recursorversion=0.0.0 <5.5.0

Published CVSS scores

3.7Open-XchangeCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

No sourced classifications are available.

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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