CVE-2026-82309

MEDIUMPre-NVD 4.34.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 4.3 under CISA-ADP (Vulnrichment) CVSS v3.1 (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 85% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: cisa-adp, epss
4.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 4.3Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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.

CVSS v3
4.3
EG Score
4.3(medium)
EG Risk
34(Track)
EG Risk 34/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity43% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
15%
KEV
Not listed

Published

September 4, 2026

Last Modified

September 8, 2026

Advisory Details (4)

Auto-updated Sep 8, 2026
Patch available. Sources: github.
generic

oss-security - 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 loop that does not bound the names it queries

http://www.openwall.com/lists/oss-security/2026/09/04/3
generic

Client Challenge

https://metacpan.org/release/RRWO/Robots-Validate-v0.4.0/changes
github Patch Available

one request triggers an unbounded, client-sized number of outbound DNS lookups · Advisory · robrwo/Robots-Validate · GitHub

https://github.com/robrwo/Robots-Validate/security/advisories/GHSA-6399-5qhh-48h5
generic
https://github.com/robrwo/Robots-Validate/commit/6426178c49ff6c440922f31a92a6feb3c661b143.patch

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 11× in last 7d / 27× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-19 05:16 UTCEG score recompute
  2. 2026-09-18 19:28 UTCEPSS rescore
  3. 2026-09-18 04:38 UTCEG score recompute
  4. 2026-09-17 03:59 UTCEG score recompute
  5. 2026-09-16 14:08 UTCEPSS rescore
  6. 2026-09-16 05:15 UTCEPSS rescore
  7. 2026-09-16 03:19 UTCEG score recompute
  8. 2026-09-15 03:12 UTCEPSS rescore
  9. 2026-09-15 03:12 UTCEPSS rescore
  10. 2026-09-14 02:00 UTCEG score recompute
  11. 2026-09-13 01:21 UTCEG score recompute
  12. 2026-09-12 00:42 UTCEG score recompute
  13. 2026-09-11 14:53 UTCEPSS rescore
  14. 2026-09-11 14:53 UTCEPSS rescore
  15. 2026-09-11 00:03 UTCEG score recompute
  16. 2026-09-09 23:23 UTCEG score recompute
  17. 2026-09-08 22:01 UTCEPSS rescore
  18. 2026-09-08 19:05 UTCEG score recompute▲ 4.30
  19. 2026-09-08 19:04 UTCMITRE cvelistV5CVSS v3 → 4.3 · severity → MEDIUM
  20. 2026-09-07 18:10 UTCEG score recompute
  21. 2026-09-06 13:48 UTCEPSS rescore
  22. 2026-09-05 15:31 UTCEPSS rescore
  23. 2026-09-04 15:20 UTCNVD update
  24. 2026-09-04 15:09 UTCMITRE cvelistV5
  25. 2026-09-04 13:24 UTCNVD update
Show 2 more
  1. 2026-09-04 12:45 UTCEG score recompute
  2. 2026-09-04 12:43 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-82309?
CVE-2026-82309 is a medium vulnerability published on September 4, 2026. 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. checkdns issues one PTR query for the client address, keeps the returned names matching the rule's domain, and…
When was CVE-2026-82309 disclosed?
CVE-2026-82309 was first published in the National Vulnerability Database on September 4, 2026, with the most recent update on September 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-82309 actively exploited?
CVE-2026-82309 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0% probability of exploitation in the next 30 days, which ranks it in the top 84.8% of all scored CVEs.
What is the CVSS score of CVE-2026-82309?
CVE-2026-82309 has a CVSS v3.1 base score of 4.3 (CISA-ADP / Vulnrichment enrichment; NVD's own analysis pending).
How do I remediate CVE-2026-82309?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-82309, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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