CVE-2026-42578

HIGHNVD 7.52.9▼
EchelonGraph scoreMEDIUM confidence

This low-severity CVE scores 2.9 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit probability: 0.4%, top 67% 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: cna:github_m, epss
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.

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's HttpProxyHandler constructs HTTP CONNECT requests with header validation explicitly disabled. The newInitialMessage() method creates headers using DefaultHttpHeadersFactory.headersFactory().withValidation(false), then adds user-provided outboundHeaders without any CRLF validation. This allows an attacker who can influence the outbound headers to inject arbitrary HTTP headers into the CONNECT request sent to the proxy server. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

CVSS v3
7.5
EG Score
2.9(medium)
EPSS
56.3%
KEV
Not listed

Published

May 13, 2026

Last Modified

July 10, 2026

Advisory Details (1)

Auto-updated May 18, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

HTTP Header Injection via HttpProxyHandler Disabled Validation in Netty · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-45q3-82m4-75jr

Vendor Advisories for CVE-2026-42578(6)

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

Patch Availability(5)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibnetty-java (1:3.2.6.Final-2+deb8u2ubuntu0.1~esm1) @ trusty2026-06-27ubuntu
redhatcryostat/jfr-datasource-rhel9:4.2.0-102026-06-22redhat
redhatpatch2026-06-10redhat
redhatnetty-handler-proxy2026-06-10redhat
redhatdevspaces/server-rhel9:17806949942026-06-10redhat

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

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
io.netty:netty-handler-proxy4.2.0.Alpha1 ... 4.2.9.Final (23 versions)4.2.13.Final—

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 8× in last 7d / 60× 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 121 total refreshes for this CVE.

  1. 2026-07-11 08:27 UTCEPSS rescore
  2. 2026-07-09 19:10 UTCEPSS rescore
  3. 2026-07-08 15:15 UTCEPSS rescore
  4. 2026-07-07 13:46 UTCEPSS rescore
  5. 2026-07-06 16:27 UTCEPSS rescore
  6. 2026-07-06 16:27 UTCEPSS rescore
  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. 2026-07-04 06:31 UTCEPSS rescore
  11. 2026-07-01 15:06 UTCEPSS rescore
  12. 2026-06-30 23:22 UTCEPSS rescore
  13. 2026-06-30 04:33 UTCNVD updateCVSS v3 → 7.5 · severity → HIGH
  14. 2026-06-29 14:06 UTCEPSS rescore
  15. 2026-06-28 14:07 UTCEPSS rescore
  16. 2026-06-28 04:56 UTCEPSS rescore
  17. 2026-06-27 08:10 UTCEG score recompute▼ 4.60
  18. 2026-06-27 08:10 UTCVendor advisory
  19. 2026-06-27 03:17 UTCMITRE cvelistV5CVSS v3 → 2.9 · severity → LOW
  20. 2026-06-27 03:08 UTCEPSS rescore
  21. 2026-06-26 20:28 UTCEG score recompute
  22. 2026-06-26 20:28 UTCVendor advisory
  23. 2026-06-25 19:35 UTCEG score recompute
  24. 2026-06-25 19:35 UTCVendor advisory
  25. 2026-06-25 13:49 UTCEPSS rescore
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  1. 2026-06-25 13:49 UTCEPSS rescore
  2. 2026-06-24 14:05 UTCEPSS rescore
  3. 2026-06-23 21:33 UTCEPSS rescore
  4. 2026-06-22 14:25 UTCEPSS rescore
  5. 2026-06-22 14:25 UTCEPSS rescore
  6. 2026-06-21 14:56 UTCEPSS rescore
  7. 2026-06-21 14:56 UTCEPSS rescore
  8. 2026-06-21 01:59 UTCEPSS rescore
  9. 2026-06-19 19:25 UTCEPSS rescore
  10. 2026-06-18 17:52 UTCEPSS rescore
  11. 2026-06-18 17:52 UTCEPSS rescore
  12. 2026-06-17 17:53 UTCEPSS rescore
  13. 2026-06-17 14:27 UTCEG score recompute
  14. 2026-06-17 14:27 UTCVendor advisory
  15. 2026-06-16 22:31 UTCEG score recompute
  16. 2026-06-16 22:31 UTCVendor advisory
  17. 2026-06-16 17:52 UTCEPSS rescore
  18. 2026-06-16 00:39 UTCEG score recompute
  19. 2026-06-16 00:39 UTCVendor advisory
  20. 2026-06-15 17:49 UTCEPSS rescore
  21. 2026-06-14 22:57 UTCEG score recompute
  22. 2026-06-14 22:57 UTCVendor advisory
  23. 2026-06-14 11:20 UTCEG score recompute
  24. 2026-06-14 11:20 UTCVendor advisory
  25. 2026-06-13 23:43 UTCEG score recompute
  26. 2026-06-13 23:43 UTCVendor advisory
  27. 2026-06-13 23:00 UTCEPSS rescore
  28. 2026-06-13 08:25 UTCEG score recompute
  29. 2026-06-13 08:25 UTCVendor advisory
  30. 2026-06-12 23:12 UTCEPSS rescore
  31. 2026-06-12 23:12 UTCEPSS rescore
  32. 2026-06-12 20:47 UTCEG score recompute
  33. 2026-06-12 20:47 UTCVendor advisory
  34. 2026-06-12 09:10 UTCEG score recompute
  35. 2026-06-12 09:10 UTCVendor advisory
  36. 2026-06-11 21:31 UTCEG score recompute
  37. 2026-06-11 21:31 UTCVendor advisory
  38. 2026-06-11 14:00 UTCEPSS rescore
  39. 2026-06-11 09:55 UTCEG score recompute
  40. 2026-06-11 09:55 UTCVendor advisory
  41. 2026-06-10 22:18 UTCEPSS rescore
  42. 2026-06-10 22:18 UTCEG score recompute
  43. 2026-06-10 22:18 UTCVendor advisory
  44. 2026-06-10 13:22 UTCEPSS rescore
  45. 2026-06-10 13:22 UTCEPSS rescore
  46. 2026-06-10 10:41 UTCEG score recompute
  47. 2026-06-10 10:41 UTCVendor advisory
  48. 2026-06-09 23:04 UTCEG score recompute
  49. 2026-06-09 23:04 UTCVendor advisory
  50. 2026-06-09 11:28 UTCEG score recompute
  51. 2026-06-09 11:28 UTCVendor advisory
  52. 2026-06-08 23:51 UTCEG score recompute
  53. 2026-06-08 23:51 UTCVendor advisory
  54. 2026-06-08 14:17 UTCEPSS rescore
  55. 2026-06-08 14:17 UTCEPSS rescore
  56. 2026-06-08 12:14 UTCEG score recompute
  57. 2026-06-08 00:37 UTCEG score recompute
  58. 2026-06-07 15:25 UTCEPSS rescore
  59. 2026-06-07 15:25 UTCEPSS rescore
  60. 2026-06-07 13:00 UTCEG score recompute
  61. 2026-06-07 01:24 UTCEG score recompute
  62. 2026-06-06 13:47 UTCEG score recompute
  63. 2026-06-06 02:10 UTCEG score recompute
  64. 2026-06-05 22:47 UTCEPSS rescore
  65. 2026-06-05 14:34 UTCEG score recompute
  66. 2026-06-05 02:57 UTCEG score recompute
  67. 2026-06-04 15:20 UTCEG score recompute
  68. 2026-06-04 13:12 UTCEPSS rescore
  69. 2026-06-04 13:12 UTCEPSS rescore
  70. 2026-06-04 03:43 UTCEG score recompute
  71. 2026-06-03 16:06 UTCEG score recompute
  72. 2026-06-03 04:29 UTCEG score recompute
  73. 2026-06-02 20:13 UTCEPSS rescore
  74. 2026-06-02 16:52 UTCEG score recompute
  75. 2026-06-02 05:15 UTCEG score recompute

Frequently asked(5)

What is CVE-2026-42578?
CVE-2026-42578 is a high vulnerability published on May 13, 2026. Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, Netty's HttpProxyHandler constructs HTTP CONNECT requests with header validation explicitly disabled. The newInitialMessage() method creates headers using…
When was CVE-2026-42578 disclosed?
CVE-2026-42578 was first published in the National Vulnerability Database on May 13, 2026, with the most recent update on July 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42578 actively exploited?
CVE-2026-42578 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 56.3% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-42578?
CVE-2026-42578 has a CVSS v3 base score of 7.5 (NVD). EchelonGraph synthesises NVD + CISA KEV + FIRST EPSS + GHSA into a combined EG score of 2.9.
How do I remediate CVE-2026-42578?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42578, 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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