CVE-2026-55851

HIGHNVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.6%, top 53% 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 — Patch released this week
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 7.5Exploit: None knownExposed: 0

A fix is available — apply it.

Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final up to (but not including) 4.2.16.Final, and 4.1.0.Final up to (but not including) 4.1.135, the HAProxyMessageDecoder in Netty's codec-haproxy module performs protocol version detection by reading the 13th byte as a signed Java byte and widening it to int without masking; a PROXY protocol v2 binary prefix followed by version byte 0xFF sign-extends to -1, collides with the decoder's need-more-data sentinel, and causes ByteToMessageDecoder to accumulate inbound bytes in an unbounded cumulation buffer until direct memory is exhausted. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.

CVSS v3
7.5
EG Score
7.5(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: 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%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
1%
EPSS %ILE
47%
KEV
Not listed

Published

July 21, 2026

Last Modified

July 30, 2026

Advisory Details (5)

Auto-updated Jul 22, 2026
Patch available. Sources: github, github_commit, github_release.
github Patch Available

[codec-haproxy] Signed-Byte Sentinel Collision in HAProxyMessageDecoder Leads to Unbounded Memory Exhaustion · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-q6cq-mhr2-jmr5
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_commit Patch Available

commit bb2ff68a1fb7 (netty/netty)

Patch available: netty/netty netty-4.1.136.Final (contains commit bb2ff68a1fb7)

https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6
github_commit Patch Available

commit 5b68c61f37aa (netty/netty)

Patch available: netty/netty netty-4.2.16.Final (contains commit 5b68c61f37aa)

https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b

Vendor Advisories for CVE-2026-55851(7)

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

Patch Availability(2)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatnetty-codec-haproxy2026-09-10redhat
redhatrhoai/odh-trustyai-service-rhel9:17881986812026-09-08redhat

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-haproxy4.1.0.Final ... 4.1.99.Final (136 versions)4.1.136.Final—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 16× in last 7d / 90× 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 159 total refreshes for this CVE.

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

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-55851?
CVE-2026-55851 is a high vulnerability published on July 21, 2026. Netty is a network application framework for development of protocol servers and clients. In versions 4.2.0.Final up to (but not including) 4.2.16.Final, and 4.1.0.Final up to (but not including) 4.1.135, the HAProxyMessageDecoder in Netty's codec-haproxy module performs protocol version detection…
When was CVE-2026-55851 disclosed?
CVE-2026-55851 was first published in the National Vulnerability Database on July 21, 2026, with the most recent update on July 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55851 actively exploited?
CVE-2026-55851 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 52.7% of all scored CVEs.
What is the CVSS score of CVE-2026-55851?
CVE-2026-55851 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-55851?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55851, 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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