CVE-2026-59898

MEDIUMPre-NVD 6.36.3—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 82% 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, secondary
Trending — Patch released this week
6.3EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.3Exploit: 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, ab attacker can force WebSocket upgrade via the lax V07 (or V08) handshaker by sending Sec-WebSocket-Version: 7 and omitting Connection: Upgrade / Upgrade: websocket headers, completing a protocol switch that a proxy would not recognize as an Upgrade request and enabling HTTP request smuggling / protocol-confusion attacks. This issue has been fixed in versions 4.1.136.Final and 4.2.16.Final.

CVSS v3
6.3
EG Score
6.3(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
Severity63% × 45%
Exploitation0% × 40%
Automatability0% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
18%
KEV
Not listed

Published

July 22, 2026

Last Modified

July 30, 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

WebSockets V07/V08 handshaker missing Connection/Upgrade validation · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-4mp9-239f-g9hg

Vendor Advisories for CVE-2026-59898(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-http2026-07-30redhat

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

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
io.netty:netty-codec-http4.0.0.Alpha1 ... 4.1.99.Final (229 versions)4.1.136.Final—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 9× in last 7d / 11× 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.

  1. 2026-07-30 16:34 UTCEG score recompute
  2. 2026-07-30 16:34 UTCVendor advisory
  3. 2026-07-30 16:28 UTCEPSS rescore
  4. 2026-07-30 15:40 UTCEG score recompute
  5. 2026-07-30 15:40 UTCVendor advisory
  6. 2026-07-29 19:35 UTCEG score recompute
  7. 2026-07-29 18:34 UTCEG score recompute▲ 6.30
  8. 2026-07-29 18:32 UTCMITRE cvelistV5CVSS v3 → 6.3 · CVSS v4 → 6.3
  9. 2026-07-29 11:48 UTCEG score recompute
  10. 2026-07-23 03:21 UTCEG score recompute
  11. 2026-07-22 22:27 UTCEG score recompute

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-59898?
CVE-2026-59898 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, ab attacker can force WebSocket upgrade via the lax V07 (or V08) handshaker by sending Sec-WebSocket-Version: 7 and omitting Connection: Upgrade / Upgrade: websocket headers,…
When was CVE-2026-59898 disclosed?
CVE-2026-59898 was first published in the National Vulnerability Database on July 22, 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-2026-59898 actively exploited?
CVE-2026-59898 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 81.6% of all scored CVEs.
What is the CVSS score of CVE-2026-59898?
CVE-2026-59898 has a CVSS v3 base score of 6.3 (NVD).
How do I remediate CVE-2026-59898?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-59898, 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

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-59898

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