Robots::Validate versions from 0.3.2 before 0.3.11 for Perl allow unbounded outbound DNS queries per validation via a forward-confirmation loop that does not bound the names it queries.

_check_dns issues one PTR query for the client address, keeps the returned names matching the rule's domain, and issues a forward query for each until one resolves back to that address. Nothing bounds that list, and a client controls the reverse zone for its own address, so it chooses how many names the PTR answer holds. Net::DNS refetches a truncated answer over TCP by default, so the 512-byte UDP payload does not cap it either.

Any client whose User-Agent matches a rule with a domain reaches _check_dns. Each forward name is distinct and client-chosen, so every query misses the local cache and is resolved against the authoritative servers for that domain. The queries are synchronous, so the caller is held until all of them answer or time out.
Advisories

No advisories yet.

Fixes

Solution

Upgrade to Robots-Validate 0.3.11 or later.


Workaround

No workaround given by the vendor.

History

Fri, 04 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
References

Fri, 04 Sep 2026 12:45:00 +0000

Type Values Removed Values Added
Description Robots::Validate versions from 0.3.2 before 0.3.11 for Perl allow unbounded outbound DNS queries per validation via a forward-confirmation loop that does not bound the names it queries. _check_dns issues one PTR query for the client address, keeps the returned names matching the rule's domain, and issues a forward query for each until one resolves back to that address. Nothing bounds that list, and a client controls the reverse zone for its own address, so it chooses how many names the PTR answer holds. Net::DNS refetches a truncated answer over TCP by default, so the 512-byte UDP payload does not cap it either. Any client whose User-Agent matches a rule with a domain reaches _check_dns. Each forward name is distinct and client-chosen, so every query misses the local cache and is resolved against the authoritative servers for that domain. The queries are synchronous, so the caller is held until all of them answer or time out.
Title Robots::Validate versions from 0.3.2 before 0.3.11 for Perl allow unbounded outbound DNS queries per validation via a forward-confirmation loop that does not bound the names it queries
Weaknesses CWE-405
CWE-770
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: CPANSec

Published:

Updated: 2026-09-04T15:07:21.822Z

Reserved: 2026-08-28T12:56:46.972Z

Link: CVE-2026-82309

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-04T13:20:10.667

Modified: 2026-09-04T15:17:35.840

Link: CVE-2026-82309

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-04T14:00:05Z

Weaknesses