CPANSA-Robots-Validate-2026-82309: Robots-Validate vulnerability

Publisher giterlizzi Document category csaf_security_advisory
Initial release date 2026-09-04T00:00:00 Engine CSAF Perl Toolkit 0.26
Current release date 2026-09-04T00:00:00 Build Date
Current version 1 Status final
CVSS v3.1 Base Score Severity
Original language Language en
Also referred to

Vulnerability 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.

Vulnerabilities

CVE-2026-82309

Vulnerability 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.

Weakness CWE-405 : Asymmetric Resource Consumption (Amplification)

Product status

Known affected
Product Score
Robots-Validate greater than or equal 0.3.2 and less than 0.3.11
CVSS Version CVSS Vector CVSS Base Score CVSS Base Severity
Fixed

giterlizzi

Namespace: https://github.com/giterlizzi/

gdt@cpan.org

References

Revision history

Version Date of the revision Summary of the revision
1 Fri Sep 4 00:00:00 2026 First release

Sharing rules

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