CVE-2026-40209

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreHIGH confidence

Score 5.3 from GitHub Security Advisory published 2026-06-25. a secondary CVSS source baseline 5.3; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
5.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 0%CVSS: 5.3Exploit: NoneExposed: 0

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

An attacker might be able to cause outgoing TCP connections to backend to be stuck until a timeout occurs instead of being released immediately, by sending IXFR queries. This could be used to cause a denial of service if there is a limit to the number of concurrent connections to this backend, or if the process runs out of file descriptors.

CVSS v3
5.3
EG Score
5.3(high)
EG Risk
29(Track)
EG Risk 29/100SSVC: 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
Severity53% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
33.0%
KEV
Not listed

Published

June 25, 2026

Last Modified

June 25, 2026

Advisory Details (1)

Auto-updated Jun 25, 2026
No patch confirmed yet.
generic

PowerDNS Security Advisory 2026-09 for DNSdist: Multiple issues - dnsdist documentation

https://www.dnsdist.org/security-advisories/powerdns-advisory-for-dnsdist-2026-09.html

Vendor Advisories for CVE-2026-40209(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 55× 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. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 14:18 UTCEPSS rescore
  3. 2026-07-23 03:11 UTCEG score recompute
  4. 2026-07-22 14:08 UTCEPSS rescore
  5. 2026-07-21 15:24 UTCEPSS rescore
  6. 2026-07-20 17:08 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 02:29 UTCEPSS rescore
  9. 2026-07-18 10:04 UTCEPSS rescore
  10. 2026-07-16 17:03 UTCEPSS rescore
  11. 2026-07-16 06:53 UTCGHSA enrichment
  12. 2026-07-15 16:57 UTCEPSS rescore
  13. 2026-07-15 16:57 UTCEPSS rescore
  14. 2026-07-15 06:08 UTCGHSA enrichment
  15. 2026-07-15 02:00 UTCEPSS rescore
  16. 2026-07-14 03:34 UTCGHSA enrichment
  17. 2026-07-13 22:30 UTCEPSS rescore
  18. 2026-07-13 06:13 UTCEPSS rescore
  19. 2026-07-13 06:13 UTCEPSS rescore
  20. 2026-07-13 02:56 UTCGHSA enrichment
  21. 2026-07-12 05:46 UTCEPSS rescore
  22. 2026-07-12 02:18 UTCGHSA enrichment
  23. 2026-07-11 08:27 UTCEPSS rescore
  24. 2026-07-11 01:40 UTCGHSA enrichment
  25. 2026-07-10 00:54 UTCGHSA enrichment
Show 30 more
  1. 2026-07-09 19:10 UTCEPSS rescore
  2. 2026-07-09 00:09 UTCGHSA enrichment
  3. 2026-07-08 15:15 UTCEPSS rescore
  4. 2026-07-07 23:30 UTCGHSA enrichment
  5. 2026-07-07 13:46 UTCEPSS rescore
  6. 2026-07-06 22:53 UTCGHSA enrichment
  7. 2026-07-06 16:27 UTCEPSS rescore
  8. 2026-07-06 16:27 UTCEPSS rescore
  9. 2026-07-06 02:23 UTCEPSS rescore
  10. 2026-07-06 02:23 UTCEPSS rescore
  11. 2026-07-05 22:15 UTCGHSA enrichment
  12. 2026-07-05 02:30 UTCEPSS rescore
  13. 2026-07-04 21:37 UTCGHSA enrichment
  14. 2026-07-04 06:31 UTCEPSS rescore
  15. 2026-07-03 20:59 UTCGHSA enrichment
  16. 2026-07-02 20:21 UTCGHSA enrichment
  17. 2026-07-01 19:43 UTCGHSA enrichment
  18. 2026-07-01 15:06 UTCEPSS rescore
  19. 2026-06-30 23:22 UTCEPSS rescore
  20. 2026-06-30 19:06 UTCGHSA enrichment
  21. 2026-06-29 18:25 UTCGHSA enrichment
  22. 2026-06-29 14:06 UTCEPSS rescore
  23. 2026-06-28 17:45 UTCGHSA enrichment
  24. 2026-06-28 14:07 UTCEPSS rescore
  25. 2026-06-28 04:56 UTCEPSS rescore
  26. 2026-06-27 17:05 UTCGHSA enrichment
  27. 2026-06-27 03:08 UTCEPSS rescore
  28. 2026-06-26 16:27 UTCGHSA enrichment
  29. 2026-06-25 15:50 UTCEG score recompute
  30. 2026-06-25 15:50 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2026-40209?
CVE-2026-40209 is a medium vulnerability published on June 25, 2026. An attacker might be able to cause outgoing TCP connections to backend to be stuck until a timeout occurs instead of being released immediately, by sending IXFR queries. This could be used to cause a denial of service if there is a limit to the number of concurrent connections to this backend, or…
When was CVE-2026-40209 disclosed?
CVE-2026-40209 was first published in the National Vulnerability Database on June 25, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40209 actively exploited?
CVE-2026-40209 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 33.0% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-40209?
CVE-2026-40209 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-40209?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40209, 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.

Dependency Blast Radius

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