---
id: CVE-2026-82309
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.


  _check_dns issues one PTR query for the client add…
summary: >-
  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 add…
severity: medium
cvss: 4.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-405
  - CWE-770
product: Robots-Validate
affected:
  - Robots-Validate >= 0.3.2 < 0.3.11
published: '2026-09-04'
updated: '2026-09-08'
sourceUpdated: '2026-09-08T19:20:00.593'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-82309'
references:
  - url: >-
      https://github.com/robrwo/Robots-Validate/commit/6426178c49ff6c440922f31a92a6feb3c661b143.patch
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: >-
      https://github.com/robrwo/Robots-Validate/security/advisories/GHSA-6399-5qhh-48h5
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'https://metacpan.org/release/RRWO/Robots-Validate-v0.4.0/changes'
    label: 9b29abf9-4ab0-4765-b253-1875cd9b441e
  - url: 'http://www.openwall.com/lists/oss-security/2026/09/04/3'
    label: af854a3a-2127-422b-91ae-364da2661108
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: partial
  timestamp: '2026-09-08T18:56:08.513256Z'
epss: 0.00239
epssPercentile: 0.15186
ingestedAt: '2026-09-08T15:33:26.960Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.