CVE-2026-40211

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 can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory condition, resulting in a denial of service.

CVSS v3
5.3
EG Score
5.3(high)
EPSS
33.2%
KEV
Not listed

Published

June 25, 2026

Last Modified

June 25, 2026

Advisory Details (1)

Auto-updated Jun 27, 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-2026-40211(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 / 35× 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. 2026-07-07 03:58 UTCEG score recompute
  2. 2026-07-07 03:58 UTCGHSA enrichment
  3. 2026-07-06 16:27 UTCEPSS rescore
  4. 2026-07-06 16:27 UTCEPSS rescore
  5. 2026-07-06 02:39 UTCEG score recompute
  6. 2026-07-06 02:39 UTCGHSA enrichment
  7. 2026-07-06 02:23 UTCEPSS rescore
  8. 2026-07-06 02:23 UTCEPSS rescore
  9. 2026-07-05 02:30 UTCEPSS rescore
  10. 2026-07-05 01:34 UTCEG score recompute
  11. 2026-07-05 01:34 UTCGHSA enrichment
  12. 2026-07-04 06:31 UTCEPSS rescore
  13. 2026-07-04 00:28 UTCEG score recompute
  14. 2026-07-04 00:28 UTCGHSA enrichment
  15. 2026-07-02 23:24 UTCEG score recompute
  16. 2026-07-02 23:24 UTCGHSA enrichment
  17. 2026-07-01 22:20 UTCEG score recompute
  18. 2026-07-01 22:20 UTCGHSA enrichment
  19. 2026-07-01 15:06 UTCEPSS rescore
  20. 2026-06-30 23:22 UTCEPSS rescore
  21. 2026-06-30 21:13 UTCEG score recompute
  22. 2026-06-30 21:13 UTCGHSA enrichment
  23. 2026-06-29 20:07 UTCEG score recompute
  24. 2026-06-29 20:07 UTCGHSA enrichment
  25. 2026-06-28 19:03 UTCEG score recompute
Show 10 more
  1. 2026-06-28 19:03 UTCGHSA enrichment
  2. 2026-06-28 14:07 UTCEPSS rescore
  3. 2026-06-28 04:56 UTCEPSS rescore
  4. 2026-06-27 17:59 UTCEG score recompute
  5. 2026-06-27 17:59 UTCGHSA enrichment
  6. 2026-06-27 03:08 UTCEPSS rescore
  7. 2026-06-26 16:54 UTCEG score recompute
  8. 2026-06-26 16:54 UTCGHSA enrichment
  9. 2026-06-25 15:50 UTCEG score recompute
  10. 2026-06-25 15:50 UTCGHSA enrichment

Frequently asked(5)

What is CVE-2026-40211?
CVE-2026-40211 is a medium vulnerability published on June 25, 2026. An attacker can send crafted DNS over HTTP/3 queries, triggering an exception that prevents some buffer from being freed right away. The buffer will be freed at the end of the QUIC connection, but on some setups it might be possible to open enough concurrent DoH3 streams to trigger an out-of-memory…
When was CVE-2026-40211 disclosed?
CVE-2026-40211 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-2026-40211 actively exploited?
CVE-2026-40211 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 33.2% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-40211?
CVE-2026-40211 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-40211?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40211, 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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