CVE-2026-52684: Time-of-check Time-of-use (TOCTOU) Race Condition in PowerDNS Recursor
If the auth responds very slowly and the records expire in between, the capping of TTLs is not enforced for lack of data. This does not happen on regular resolve as then then the child records are used immediately if not expired and thus valid, or the records are expired, and in that case not used. So this case can only happen if almost expired records are used to refresh the authoritative NS records.
AI Analysis
Technical Summary
This vulnerability in PowerDNS Recursor arises from a TOCTOU race condition where slow authoritative responses combined with record expiration lead to improper enforcement of TTL capping. The flaw manifests only during the refresh of authoritative NS records using nearly expired records. Under normal resolution, this condition does not occur as valid child records are used immediately or expired records are discarded. The issue affects versions from 0.0.0 up to but not including 5.5.0. The CVSS v3.1 base score is 3.7, indicating low severity, with no confidentiality or availability impact, only low integrity impact. No patch or vendor advisory is currently available.
Potential Impact
The vulnerability can cause improper TTL capping enforcement during authoritative NS record refreshes when authoritative responses are slow and records expire mid-process. This may lead to low integrity issues in DNS resolution behavior. There is no impact on confidentiality or availability. No known exploits have been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, monitor for vendor updates. No specific mitigations are documented at this time.
CVE-2026-52684: Time-of-check Time-of-use (TOCTOU) Race Condition in PowerDNS Recursor
Description
If the auth responds very slowly and the records expire in between, the capping of TTLs is not enforced for lack of data. This does not happen on regular resolve as then then the child records are used immediately if not expired and thus valid, or the records are expired, and in that case not used. So this case can only happen if almost expired records are used to refresh the authoritative NS records.
CVSS v3.1
Score 3.7low
Affected software
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AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability in PowerDNS Recursor arises from a TOCTOU race condition where slow authoritative responses combined with record expiration lead to improper enforcement of TTL capping. The flaw manifests only during the refresh of authoritative NS records using nearly expired records. Under normal resolution, this condition does not occur as valid child records are used immediately or expired records are discarded. The issue affects versions from 0.0.0 up to but not including 5.5.0. The CVSS v3.1 base score is 3.7, indicating low severity, with no confidentiality or availability impact, only low integrity impact. No patch or vendor advisory is currently available.
Potential Impact
The vulnerability can cause improper TTL capping enforcement during authoritative NS record refreshes when authoritative responses are slow and records expire mid-process. This may lead to low integrity issues in DNS resolution behavior. There is no impact on confidentiality or availability. No known exploits have been reported.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until an official fix is released, monitor for vendor updates. No specific mitigations are documented at this time.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- OX
- Date Reserved
- 2026-06-08T08:05:31.707Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a61d2cf9c2644c7f8b6a265
Added to database: 07/23/2026, 08:37:35 UTC
Last enriched: 07/23/2026, 08:52:38 UTC
Last updated: 09/04/2026, 22:52:12 UTC
Views: 101
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