CVE-2026-40170

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.0%, top 93% 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
Elevated
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

A fix is available — apply it.

ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2_qlog_parameters_set_transport_params() serializes peer transport parameters into a fixed 1024-byte stack buffer without bounds checking. When qlog is enabled, a remote peer can send sufficiently large transport parameters during the QUIC handshake to cause writes beyond the buffer boundary, resulting in a stack buffer overflow. This affects deployments that enable the qlog callback and process untrusted peer transport parameters. This issue has been fixed in version 1.22.1. If developers are unable to immediately upgrade, they can disable the qlog on client.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
51.6%
KEV
Not listed

Published

April 16, 2026

Last Modified

July 15, 2026

Advisory Details (3)

Auto-updated Jun 11, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
github Patch Available🟡 PoC Available

qlog_parameters_set_transport_params_stack_overflow · Advisory · ngtcp2/ngtcp2 · GitHub

https://github.com/ngtcp2/ngtcp2/security/advisories/GHSA-f523-465f-8c8f
generic

oss-security - ngtcp2: qlog_parameters_set_transport_params_stack_overflow [CVE-2026-40170]

http://www.openwall.com/lists/oss-security/2026/04/17/12
github_commit

commit 708a7640c1f4 (ngtcp2/ngtcp2)

Fix landed in ngtcp2/ngtcp2 commit 708a7640c1f4 — awaiting tagged release

https://github.com/ngtcp2/ngtcp2/commit/708a7640c1f48fb8ffb540c4b8ea5b4c1dfb8ee5

Vendor Advisories for CVE-2026-40170(4)

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

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibngtcp2-dev (1.16.0-1ubuntu0.1) @ resolute2026-06-14ubuntu
redhatsamba-0:4.23.5-10.el9_82026-06-10redhat
redhatsamba-0:4.23.5-109.el10_22026-06-03redhat
redhatngtcp2-main-1.22.1-1.hum12026-04-20redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Weakness Classification(2)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 9× in last 7d / 37× 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 118 total refreshes for this CVE.

  1. 2026-07-15 16:57 UTCEPSS rescore
  2. 2026-07-15 16:57 UTCEPSS rescore
  3. 2026-07-15 02:00 UTCEPSS rescore
  4. 2026-07-13 22:30 UTCEPSS rescore
  5. 2026-07-13 06:13 UTCEPSS rescore
  6. 2026-07-13 06:13 UTCEPSS rescore
  7. 2026-07-12 05:46 UTCEPSS rescore
  8. 2026-07-11 08:27 UTCEPSS rescore
  9. 2026-07-09 19:10 UTCEPSS rescore
  10. 2026-07-08 15:15 UTCEPSS rescore
  11. 2026-07-07 13:46 UTCEPSS rescore
  12. 2026-07-06 16:27 UTCEPSS rescore
  13. 2026-07-06 16:27 UTCEPSS rescore
  14. 2026-07-06 02:23 UTCEPSS rescore
  15. 2026-07-06 02:23 UTCEPSS rescore
  16. 2026-07-05 02:30 UTCEPSS rescore
  17. 2026-07-04 06:31 UTCEPSS rescore
  18. 2026-07-01 15:06 UTCEPSS rescore
  19. 2026-06-30 23:22 UTCEPSS rescore
  20. 2026-06-29 14:06 UTCEPSS rescore
  21. 2026-06-28 14:07 UTCEPSS rescore
  22. 2026-06-28 04:56 UTCEPSS rescore
  23. 2026-06-27 03:08 UTCEPSS rescore
  24. 2026-06-25 13:49 UTCEPSS rescore
  25. 2026-06-25 13:49 UTCEPSS rescore
Show 75 more
  1. 2026-06-24 14:05 UTCEPSS rescore
  2. 2026-06-23 21:33 UTCEPSS rescore
  3. 2026-06-22 14:25 UTCEPSS rescore
  4. 2026-06-22 14:25 UTCEPSS rescore
  5. 2026-06-21 14:56 UTCEPSS rescore
  6. 2026-06-21 14:56 UTCEPSS rescore
  7. 2026-06-21 01:59 UTCEPSS rescore
  8. 2026-06-19 19:25 UTCEPSS rescore
  9. 2026-06-18 17:52 UTCEPSS rescore
  10. 2026-06-18 17:52 UTCEPSS rescore
  11. 2026-06-17 17:53 UTCEPSS rescore
  12. 2026-06-16 17:52 UTCEPSS rescore
  13. 2026-06-15 17:49 UTCEPSS rescore
  14. 2026-06-14 19:51 UTCEG score recompute
  15. 2026-06-14 19:51 UTCVendor advisory
  16. 2026-06-13 23:00 UTCEPSS rescore
  17. 2026-06-12 23:12 UTCEPSS rescore
  18. 2026-06-12 23:12 UTCEPSS rescore
  19. 2026-06-12 06:15 UTCEG score recompute
  20. 2026-06-12 06:15 UTCVendor advisory
  21. 2026-06-11 18:52 UTCEG score recompute
  22. 2026-06-11 18:52 UTCVendor advisory
  23. 2026-06-11 14:00 UTCEPSS rescore
  24. 2026-06-10 22:59 UTCEG score recompute
  25. 2026-06-10 22:59 UTCVendor advisory
  26. 2026-06-10 22:18 UTCEPSS rescore
  27. 2026-06-10 13:22 UTCEPSS rescore
  28. 2026-06-10 13:22 UTCEPSS rescore
  29. 2026-06-10 11:38 UTCEG score recompute
  30. 2026-06-10 11:38 UTCVendor advisory
  31. 2026-06-10 00:18 UTCEG score recompute
  32. 2026-06-10 00:18 UTCVendor advisory
  33. 2026-06-09 10:01 UTCEG score recompute
  34. 2026-06-09 10:01 UTCVendor advisory
  35. 2026-06-08 15:01 UTCEG score recompute
  36. 2026-06-08 15:01 UTCVendor advisory
  37. 2026-06-08 14:17 UTCEPSS rescore
  38. 2026-06-08 14:17 UTCEPSS rescore
  39. 2026-06-08 03:41 UTCEG score recompute
  40. 2026-06-08 03:41 UTCVendor advisory
  41. 2026-06-07 16:21 UTCEG score recompute
  42. 2026-06-07 16:21 UTCVendor advisory
  43. 2026-06-07 15:25 UTCEPSS rescore
  44. 2026-06-07 15:25 UTCEPSS rescore
  45. 2026-06-07 05:01 UTCEG score recompute
  46. 2026-06-07 05:01 UTCVendor advisory
  47. 2026-06-06 13:47 UTCEPSS rescore
  48. 2026-06-06 13:47 UTCEPSS rescore
  49. 2026-06-06 07:08 UTCEG score recompute
  50. 2026-06-06 07:08 UTCVendor advisory
  51. 2026-06-05 22:47 UTCEPSS rescore
  52. 2026-06-05 22:47 UTCEPSS rescore
  53. 2026-06-05 12:13 UTCEG score recompute
  54. 2026-06-05 12:13 UTCVendor advisory
  55. 2026-06-05 06:10 UTCEPSS rescore
  56. 2026-06-05 06:10 UTCEPSS rescore
  57. 2026-06-04 20:54 UTCEG score recompute
  58. 2026-06-04 20:54 UTCVendor advisory
  59. 2026-06-04 13:12 UTCEPSS rescore
  60. 2026-06-04 13:12 UTCEPSS rescore
  61. 2026-06-03 18:02 UTCEG score recompute
  62. 2026-06-03 18:02 UTCVendor advisory
  63. 2026-06-02 20:13 UTCEPSS rescore
  64. 2026-06-02 14:01 UTCEG score recompute
  65. 2026-06-02 14:01 UTCVendor advisory
  66. 2026-06-01 17:57 UTCEG score recompute
  67. 2026-06-01 17:57 UTCVendor advisory
  68. 2026-06-01 13:52 UTCEPSS rescore
  69. 2026-06-01 13:52 UTCEPSS rescore
  70. 2026-06-01 13:51 UTCEPSS rescore
  71. 2026-05-31 22:30 UTCEPSS rescore
  72. 2026-05-31 22:30 UTCEPSS rescore
  73. 2026-05-31 00:16 UTCEPSS rescore
  74. 2026-05-31 00:16 UTCEPSS rescore
  75. 2026-05-31 00:16 UTCEPSS rescore

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-40170?
CVE-2026-40170 is a high vulnerability published on April 16, 2026. ngtcp2 is a C implementation of the IETF QUIC protocol. In versions prior to 1.22.1, ngtcp2qlogparameterssettransport_params() serializes peer transport parameters into a fixed 1024-byte stack buffer without bounds checking. When qlog is enabled, a remote peer can send sufficiently large transport…
When was CVE-2026-40170 disclosed?
CVE-2026-40170 was first published in the National Vulnerability Database on April 16, 2026, with the most recent update on July 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-40170 actively exploited?
CVE-2026-40170 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 51.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-40170?
CVE-2026-40170 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-40170?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-40170, 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-2026-40170

Explore →

Is Your Infrastructure Affected by CVE-2026-40170?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs