CVE-2026-59900

MEDIUMNVD 5.35.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 5.3 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 86% 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
Trending — 3 sources updated this week
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

A fix is available — apply it.

Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, Netty's HTTP/2-to-HTTP/1.x translation layer (Http2StreamFrameToHttpObjectCodec and InboundHttp2ToHttpAdapter) fails to deduplicate or validate Host headers when an HTTP/2 client supplies both the :authority pseudo-header and a literal host header in a single HEADERS frame. The translator maps :authority to Host and separately copies the literal host header, producing an HttpRequest object containing two Host headers with attacker-controlled differing values. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

CVSS v3
5.3
EG Score
5.3(medium)
EG Risk
28(Track)
EG Risk 28/100SSVC: 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%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
14%
KEV
Not listed

Published

July 22, 2026

Last Modified

August 6, 2026

Advisory Details (3)

Auto-updated Jul 29, 2026
Patch available. Sources: github, github_release.
github_release Patch Available

netty-4.2.16.Final

Patch available: netty/netty netty-4.2.16.Final

https://github.com/netty/netty/releases/tag/netty-4.2.16.Final
github_release Patch Available

netty-4.1.136.Final

Patch available: netty/netty netty-4.1.136.Final

https://github.com/netty/netty/releases/tag/netty-4.1.136.Final
github Patch Available

[codec-http2] Lack of Host Header Deduplication in HTTP/2→HTTP/1.x Translation Leads to Request Routing Bypass · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-c69g-56f8-xwqj

Vendor Advisories for CVE-2026-59900(3)

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

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatnetty-codec-http22026-07-30redhat

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.

Affected Packages

(5 across 5 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
netty1:4.1.48-10 ... 1:4.1.48-9 (16 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
netty1:4.1.48-10 ... 1:4.1.48-9 (12 versions)——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
netty1:4.1.48-10 ... 1:4.1.48-16 (8 versions)——
Debian:14(1)
PackageVulnerable rangeFixed inDependents
netty1:4.1.48-10 ... 1:4.1.48-16 (7 versions)——
Maven(1)
PackageVulnerable rangeFixed inDependents
io.netty:netty-codec-http24.1.0.Beta4 ... 4.1.99.Final (148 versions)4.1.136.Final—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 15× in last 7d / 69× 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 128 total refreshes for this CVE.

  1. 2026-09-15 03:11 UTCEPSS rescore
  2. 2026-09-14 16:44 UTCEG score recompute
  3. 2026-09-14 16:44 UTCVendor advisory
  4. 2026-09-13 16:47 UTCEPSS rescore
  5. 2026-09-13 15:54 UTCVendor advisory
  6. 2026-09-12 17:48 UTCEG score recompute
  7. 2026-09-12 17:48 UTCVendor advisory
  8. 2026-09-11 19:33 UTCEG score recompute
  9. 2026-09-11 19:33 UTCVendor advisory
  10. 2026-09-11 14:53 UTCEPSS rescore
  11. 2026-09-10 21:15 UTCEG score recompute
  12. 2026-09-10 21:15 UTCVendor advisory
  13. 2026-09-10 09:35 UTCEPSS rescore
  14. 2026-09-09 09:11 UTCEG score recompute
  15. 2026-09-09 09:11 UTCVendor advisory
  16. 2026-09-08 22:01 UTCEPSS rescore
  17. 2026-09-07 21:39 UTCEG score recompute
  18. 2026-09-07 21:39 UTCVendor advisory
  19. 2026-09-07 16:01 UTCEPSS rescore
  20. 2026-09-06 17:38 UTCEG score recompute
  21. 2026-09-06 17:38 UTCVendor advisory
  22. 2026-09-06 13:47 UTCEPSS rescore
  23. 2026-09-05 19:33 UTCEG score recompute
  24. 2026-09-05 19:33 UTCVendor advisory
  25. 2026-09-04 13:39 UTCEG score recompute
Show 75 more
  1. 2026-09-04 13:39 UTCVendor advisory
  2. 2026-09-04 05:07 UTCEPSS rescore
  3. 2026-09-02 14:12 UTCEPSS rescore
  4. 2026-09-01 23:37 UTCEG score recompute
  5. 2026-09-01 23:37 UTCVendor advisory
  6. 2026-09-01 13:54 UTCEPSS rescore
  7. 2026-09-01 04:40 UTCEPSS rescore
  8. 2026-08-30 22:55 UTCEG score recompute
  9. 2026-08-30 22:55 UTCVendor advisory
  10. 2026-08-30 19:17 UTCEPSS rescore
  11. 2026-08-30 01:22 UTCEPSS rescore
  12. 2026-08-30 00:50 UTCEG score recompute
  13. 2026-08-30 00:50 UTCVendor advisory
  14. 2026-08-28 21:42 UTCEPSS rescore
  15. 2026-08-27 14:25 UTCEPSS rescore
  16. 2026-08-27 10:15 UTCEG score recompute
  17. 2026-08-27 10:15 UTCVendor advisory
  18. 2026-08-26 14:46 UTCEPSS rescore
  19. 2026-08-26 07:31 UTCEG score recompute
  20. 2026-08-26 07:31 UTCVendor advisory
  21. 2026-08-25 13:49 UTCEPSS rescore
  22. 2026-08-25 09:25 UTCEG score recompute
  23. 2026-08-25 09:25 UTCVendor advisory
  24. 2026-08-24 11:20 UTCEG score recompute
  25. 2026-08-24 11:20 UTCVendor advisory
  26. 2026-08-23 13:14 UTCEG score recompute
  27. 2026-08-23 13:14 UTCVendor advisory
  28. 2026-08-23 00:19 UTCEPSS rescore
  29. 2026-08-22 15:00 UTCEG score recompute
  30. 2026-08-22 15:00 UTCVendor advisory
  31. 2026-08-21 23:49 UTCEPSS rescore
  32. 2026-08-21 16:54 UTCEG score recompute
  33. 2026-08-21 16:54 UTCVendor advisory
  34. 2026-08-20 22:55 UTCEPSS rescore
  35. 2026-08-20 18:47 UTCVendor advisory
  36. 2026-08-19 20:42 UTCEG score recompute
  37. 2026-08-19 20:42 UTCVendor advisory
  38. 2026-08-19 17:04 UTCEPSS rescore
  39. 2026-08-18 19:44 UTCEG score recompute
  40. 2026-08-18 19:44 UTCVendor advisory
  41. 2026-08-18 13:48 UTCEPSS rescore
  42. 2026-08-17 21:37 UTCEG score recompute
  43. 2026-08-17 21:37 UTCVendor advisory
  44. 2026-08-17 13:47 UTCEPSS rescore
  45. 2026-08-16 23:32 UTCEG score recompute
  46. 2026-08-16 23:32 UTCVendor advisory
  47. 2026-08-16 14:56 UTCEPSS rescore
  48. 2026-08-16 02:14 UTCEPSS rescore
  49. 2026-08-16 01:27 UTCVendor advisory
  50. 2026-08-15 03:22 UTCEG score recompute
  51. 2026-08-15 03:22 UTCVendor advisory
  52. 2026-08-15 01:30 UTCEPSS rescore
  53. 2026-08-14 05:17 UTCEG score recompute
  54. 2026-08-14 05:17 UTCVendor advisory
  55. 2026-08-13 22:00 UTCEPSS rescore
  56. 2026-08-13 07:12 UTCEG score recompute
  57. 2026-08-13 07:12 UTCVendor advisory
  58. 2026-08-12 13:51 UTCEPSS rescore
  59. 2026-08-12 09:06 UTCEG score recompute
  60. 2026-08-12 09:06 UTCVendor advisory
  61. 2026-08-11 11:00 UTCEG score recompute
  62. 2026-08-11 11:00 UTCVendor advisory
  63. 2026-08-11 00:00 UTCEPSS rescore
  64. 2026-08-10 12:55 UTCVendor advisory
  65. 2026-08-09 14:51 UTCEG score recompute
  66. 2026-08-09 14:51 UTCVendor advisory
  67. 2026-08-09 13:46 UTCEPSS rescore
  68. 2026-08-08 16:46 UTCEG score recompute
  69. 2026-08-08 16:46 UTCVendor advisory
  70. 2026-08-08 16:37 UTCEPSS rescore
  71. 2026-08-07 18:40 UTCEG score recompute
  72. 2026-08-07 18:40 UTCVendor advisory
  73. 2026-08-06 20:35 UTCEG score recompute▼ 1.60
  74. 2026-08-06 20:35 UTCVendor advisory
  75. 2026-08-06 20:35 UTCNVD updateCVSS v3 → 5.3

Frequently asked(5)

What is CVE-2026-59900?
CVE-2026-59900 is a medium vulnerability published on July 22, 2026. Netty is an asynchronous, event-driven network application framework. Prior to versions 4.1.136.Final and 4.2.16.Final, Netty's HTTP/2-to-HTTP/1.x translation layer (Http2StreamFrameToHttpObjectCodec and InboundHttp2ToHttpAdapter) fails to deduplicate or validate Host headers when an HTTP/2 client…
When was CVE-2026-59900 disclosed?
CVE-2026-59900 was first published in the National Vulnerability Database on July 22, 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-2026-59900 actively exploited?
CVE-2026-59900 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 85.8% of all scored CVEs.
What is the CVSS score of CVE-2026-59900?
CVE-2026-59900 has a CVSS v3 base score of 5.3 (NVD).
How do I remediate CVE-2026-59900?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59900, 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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