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
Trending — 3 sources updated this week
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)
EPSS
32.4%
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 22× in last 7d / 36× 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. 2026-07-06 22:53 UTCEG score recompute
  2. 2026-07-06 22:53 UTCGHSA enrichment
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 02:23 UTCEPSS rescore
  6. 2026-07-06 02:23 UTCEPSS rescore
  7. 2026-07-05 22:15 UTCEG score recompute
  8. 2026-07-05 22:15 UTCGHSA enrichment
  9. 2026-07-05 02:30 UTCEPSS rescore
  10. 2026-07-04 21:38 UTCEG score recompute
  11. 2026-07-04 21:37 UTCGHSA enrichment
  12. 2026-07-04 06:31 UTCEPSS rescore
  13. 2026-07-03 20:59 UTCEG score recompute
  14. 2026-07-03 20:59 UTCGHSA enrichment
  15. 2026-07-02 20:22 UTCEG score recompute
  16. 2026-07-02 20:21 UTCGHSA enrichment
  17. 2026-07-01 19:43 UTCEG score recompute
  18. 2026-07-01 19:43 UTCGHSA enrichment
  19. 2026-07-01 15:06 UTCEPSS rescore
  20. 2026-06-30 23:22 UTCEPSS rescore
  21. 2026-06-30 19:06 UTCEG score recompute
  22. 2026-06-30 19:06 UTCGHSA enrichment
  23. 2026-06-29 18:26 UTCEG score recompute
  24. 2026-06-29 18:25 UTCGHSA enrichment
  25. 2026-06-29 14:06 UTCEPSS rescore
Show 11 more
  1. 2026-06-28 17:46 UTCEG score recompute
  2. 2026-06-28 17:45 UTCGHSA enrichment
  3. 2026-06-28 14:07 UTCEPSS rescore
  4. 2026-06-28 04:56 UTCEPSS rescore
  5. 2026-06-27 17:05 UTCEG score recompute
  6. 2026-06-27 17:05 UTCGHSA enrichment
  7. 2026-06-27 03:08 UTCEPSS rescore
  8. 2026-06-26 16:27 UTCEG score recompute
  9. 2026-06-26 16:27 UTCGHSA enrichment
  10. 2026-06-25 15:50 UTCEG score recompute
  11. 2026-06-25 15:50 UTCGHSA enrichment

Related CVEs(same CWE)

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 32.4% 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

Explore the affected products and dependency analysis for CVE-2026-40209

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