CVE-2023-50247

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.9%, top 45% 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: epss, nvd
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.5Exploit: NoneExposed: 0

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

h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. The QUIC stack (quicly), as used by H2O up to commit 43f86e5 (in version 2.3.0-beta and prior), is susceptible to a state exhaustion attack. When H2O is serving HTTP/3, a remote attacker can exploit this vulnerability to progressively increase the memory retained by the QUIC stack. This can eventually cause H2O to abort due to memory exhaustion. The vulnerability has been resolved in commit d67e81d03be12a9d53dc8271af6530f40164cd35. HTTP/1 and HTTP/2 are not affected by this vulnerability as they do not use QUIC. Administrators looking to mitigate this issue without upgrading can disable HTTP/3 support.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
39(Track)
EG Risk 39/100SSVC: 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
Severity75% × 45%
Exploitation1% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS
54.6%
KEV
Not listed

Published

December 12, 2023

Last Modified

June 17, 2026

References (4)

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 12× in last 7d / 49× 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.

Showing the most recent 100 of 105 total refreshes for this CVE.

  1. 2026-07-23 14:16 UTCEPSS rescore
  2. 2026-07-23 02:28 UTCEG score recompute
  3. 2026-07-22 23:15 UTCEG score recompute▲ 3.80
  4. 2026-07-22 14:06 UTCEPSS rescore
  5. 2026-07-21 15:23 UTCEPSS rescore
  6. 2026-07-21 15:23 UTCEPSS rescore
  7. 2026-07-20 17:06 UTCEPSS rescore
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  10. 2026-07-19 02:27 UTCEPSS rescore
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  13. 2026-07-16 17:01 UTCEPSS rescore
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  16. 2026-07-15 01:59 UTCEPSS rescore
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  18. 2026-07-15 01:40 UTCOSV refresh
  19. 2026-07-13 22:28 UTCEPSS rescore
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  21. 2026-07-13 06:11 UTCEPSS rescore
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  23. 2026-07-12 05:45 UTCEPSS rescore
  24. 2026-07-11 08:26 UTCEPSS rescore
  25. 2026-07-09 19:08 UTCEPSS rescore
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  1. 2026-07-08 15:13 UTCEPSS rescore
  2. 2026-07-07 13:44 UTCEPSS rescore
  3. 2026-07-07 13:44 UTCEPSS rescore
  4. 2026-07-06 16:26 UTCEPSS rescore
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  6. 2026-07-06 02:22 UTCEPSS rescore
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  12. 2026-06-30 23:21 UTCEPSS rescore
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  17. 2026-06-28 04:55 UTCEPSS rescore
  18. 2026-06-27 03:07 UTCEPSS rescore
  19. 2026-06-27 02:37 UTCOSV refresh
  20. 2026-06-25 13:48 UTCEPSS rescore
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  22. 2026-06-24 14:04 UTCEPSS rescore
  23. 2026-06-24 14:04 UTCEPSS rescore
  24. 2026-06-24 06:34 UTCNVD updateCVSS v3 → 7.5 · severity → HIGH
  25. 2026-06-23 21:31 UTCEPSS rescore
  26. 2026-06-23 21:31 UTCEPSS rescore
  27. 2026-06-22 14:24 UTCEPSS rescore
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  29. 2026-06-21 14:55 UTCEPSS rescore
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  31. 2026-06-21 01:58 UTCEPSS rescore
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  35. 2026-06-18 17:51 UTCEPSS rescore
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  37. 2026-06-16 17:51 UTCEPSS rescore
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  39. 2026-06-15 17:47 UTCEPSS rescore
  40. 2026-06-14 23:16 UTCEPSS rescore
  41. 2026-06-13 22:59 UTCEPSS rescore
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  43. 2026-06-12 23:11 UTCEPSS rescore
  44. 2026-06-12 23:10 UTCEPSS rescore
  45. 2026-06-11 13:59 UTCEPSS rescore
  46. 2026-06-10 22:17 UTCEPSS rescore
  47. 2026-06-10 13:21 UTCEPSS rescore
  48. 2026-06-09 12:43 UTCOSV refresh
  49. 2026-06-08 14:16 UTCEPSS rescore
  50. 2026-06-08 14:16 UTCEPSS rescore
  51. 2026-06-07 15:24 UTCEPSS rescore
  52. 2026-06-07 15:23 UTCEPSS rescore
  53. 2026-06-06 13:46 UTCEPSS rescore
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  55. 2026-06-05 22:46 UTCEPSS rescore
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  63. 2026-06-02 20:12 UTCEPSS rescore
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  65. 2026-06-01 13:51 UTCEPSS rescore
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  67. 2026-05-31 22:30 UTCEPSS rescore
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  69. 2026-05-31 00:15 UTCEPSS rescore
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  71. 2026-05-29 13:43 UTCEPSS rescore
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  73. 2026-05-27 13:39 UTCEPSS rescore
  74. 2026-05-27 13:39 UTCEPSS rescore
  75. 2026-05-26 13:43 UTCEPSS rescore

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Frequently asked(5)

What is CVE-2023-50247?
CVE-2023-50247 is a high vulnerability published on December 12, 2023. h2o is an HTTP server with support for HTTP/1.x, HTTP/2 and HTTP/3. The QUIC stack (quicly), as used by H2O up to commit 43f86e5 (in version 2.3.0-beta and prior), is susceptible to a state exhaustion attack. When H2O is serving HTTP/3, a remote attacker can exploit this vulnerability to…
When was CVE-2023-50247 disclosed?
CVE-2023-50247 was first published in the National Vulnerability Database on December 12, 2023, with the most recent update on June 17, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2023-50247 actively exploited?
CVE-2023-50247 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 54.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2023-50247?
CVE-2023-50247 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2023-50247?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2023-50247, 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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