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 52% 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
48%
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(8)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatcryostat/jfr-datasource-rhel9:4.2.0-142026-09-16redhat
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 19× in last 7d / 82× 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 181 total refreshes for this CVE.

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

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 52.1% 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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