CVE-2026-44434

MEDIUMPre-NVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.2%, top 89% 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, secondary
5.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 5.3Exploit: None knownExposed: 0

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

Quicly is an IETF QUIC protocol implementation intended primarily for use within the H2O HTTP server. Prior to commit dccf5d4, Quicly was vulnerable to stateless reset injection through lack of packet entry validation. The QUIC protocol is designed to withstand packet injection attacks, once the handshake is complete. Only packets that carry some secret patterns are considered as stateless resets. Quicly allows the peer to share up to 4 such patterns per connection. However, until now, it failed to determine which of the 4 slots that it uses to retain the secret patterns contains a valid entry. As the slots are zero-initialized, the failure meant that, unless the peer advertised 4 of such patterns, an all-zero pattern was treated as a stateless reset.In effect, this allowed an on-path attacker to reset QUIC connections governed by Quicly. This issue has been fixed by commit dccf5d4.

CVSS v3
5.3
EG Score
5.3(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
Severity53% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
11%
KEV
Not listed

Published

July 16, 2026

Last Modified

August 6, 2026

Advisory Details (2)

Auto-updated Jul 17, 2026
Patch available. Sources: github, github_commit.
github Patch Available

stateless reset injection · Advisory · h2o/quicly · GitHub

https://github.com/h2o/quicly/security/advisories/GHSA-899f-49jq-pfh8
github_commit

commit dccf5d4579c7 (h2o/quicly)

Fix landed in h2o/quicly commit dccf5d4579c7 — awaiting tagged release

https://github.com/h2o/quicly/commit/dccf5d4579c7ae9dd6e8f90c36d52e311bb60710

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 7× in last 7d / 42× 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. 2026-09-11 14:53 UTCEPSS rescore
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  1. 2026-08-21 09:26 UTCEG score recompute
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  6. 2026-08-18 13:48 UTCEPSS rescore
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  8. 2026-08-17 13:47 UTCEPSS rescore
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  10. 2026-08-16 14:56 UTCEPSS rescore
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  20. 2026-08-11 13:43 UTCEPSS rescore
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  22. 2026-08-11 00:00 UTCEPSS rescore
  23. 2026-08-10 12:47 UTCEG score recompute
  24. 2026-08-09 13:46 UTCEPSS rescore
  25. 2026-08-06 14:07 UTCEG score recompute
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  27. 2026-08-06 08:12 UTCEG score recompute
  28. 2026-08-05 19:17 UTCEPSS rescore
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  30. 2026-08-04 15:10 UTCEPSS rescore
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  35. 2026-08-01 09:46 UTCEG score recompute
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  40. 2026-07-30 01:30 UTCEPSS rescore
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  42. 2026-07-28 15:36 UTCEPSS rescore
  43. 2026-07-28 11:05 UTCEG score recompute
  44. 2026-07-27 14:13 UTCEPSS rescore
  45. 2026-07-26 11:23 UTCEG score recompute
  46. 2026-07-25 14:18 UTCEPSS rescore
  47. 2026-07-24 14:17 UTCEPSS rescore
  48. 2026-07-23 14:18 UTCEPSS rescore
  49. 2026-07-23 03:15 UTCEG score recompute
  50. 2026-07-22 14:08 UTCEPSS rescore
  51. 2026-07-21 15:24 UTCEPSS rescore
  52. 2026-07-20 17:08 UTCEPSS rescore
  53. 2026-07-19 14:31 UTCEPSS rescore
  54. 2026-07-19 02:32 UTCEG score recompute
  55. 2026-07-18 10:04 UTCEPSS rescore
  56. 2026-07-16 23:43 UTCEG score recompute
  57. 2026-07-16 23:43 UTCNVD updatefirst tracked

Frequently asked(5)

What is CVE-2026-44434?
CVE-2026-44434 is a medium vulnerability published on July 16, 2026. Quicly is an IETF QUIC protocol implementation intended primarily for use within the H2O HTTP server. Prior to commit dccf5d4, Quicly was vulnerable to stateless reset injection through lack of packet entry validation. The QUIC protocol is designed to withstand packet injection attacks, once the…
When was CVE-2026-44434 disclosed?
CVE-2026-44434 was first published in the National Vulnerability Database on July 16, 2026, with the most recent update on August 6, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-44434 actively exploited?
CVE-2026-44434 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 88.9% of all scored CVEs.
What is the CVSS score of CVE-2026-44434?
CVE-2026-44434 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-44434?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-44434, 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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