CVE-2026-82309 Robots::Validate versions from 0.3.2 before 0.3.11 for Perl allow unbounded outbound DNS queries per validation via a forward-confirmation l
Attackers can cause denial of service by triggering unbounded outbound DNS queries via a forward-confirmation loop in the Perl Robots::Validate library.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-82309?
CVE-2026-82309 is a medium-severity denial of service vulnerability, published on 4 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2026-82309?
How do I fix CVE-2026-82309?
No fix has been published for CVE-2026-82309 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-82309 being exploited?
There is no known exploitation of CVE-2026-82309 in the wild and no public exploit code.
Sources
Also known as GHSA-6399-5qhh-48h5.