Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty's SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in DefaultSpdySettingsFrame, allowing a remote SPDY/3.1 peer to send a syntactically valid roughly 2 MiB SETTINGS frame that creates 262144 map entries and amplifies network input into heap growth and ordered-map insertion work. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
CVE-2026-55831
HIGHPre-NVD 7.57.5—Trending — 3 sources updated this weekElevated
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.6%, top 54% 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
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 7.5Exploit: NoneExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EG Risk
- 39(Track)EG Risk 39/100SSVC: 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 computedSeverity75% × 45%Exploitation1% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS
- 34.7%
- KEV
- Not listed
Published
July 20, 2026
Last Modified
July 23, 2026
Advisory Details (5)
Auto-updated Jul 21, 2026🔬 Proof of concept available. Patch available. Sources: github_commit, github_release, github.
github Patch Available🟡 PoC Available
Netty SPDY SETTINGS frame count materializes unbounded settings map · Advisory · netty/netty · GitHub
https://github.com/netty/netty/security/advisories/GHSA-6jqx-86gh-f27wgithub_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.Finalgithub_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.Finalgithub_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/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6github_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/5b68c61f37aa4a3045cba624cbea239655c9003bVendor Advisories for CVE-2026-55831(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
Maven(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| io.netty:netty-codec-http | 4.1.0.Final ... 4.1.99.Final (136 versions) | 4.1.136.Final | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 9× 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.
- 2026-07-24 14:18 UTCEPSS rescore
- 2026-07-23 14:18 UTCEPSS rescore
- 2026-07-23 03:20 UTCEG score recompute
- 2026-07-22 23:26 UTCEG score recompute
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:25 UTCEPSS rescore
- 2026-07-21 01:49 UTCEG score recompute
- 2026-07-20 23:25 UTCEG score recompute
- 2026-07-20 23:23 UTCMITRE cvelistV5first tracked
Frequently asked(5)
What is CVE-2026-55831?
CVE-2026-55831 is a high vulnerability published on July 20, 2026. Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty's SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in…
When was CVE-2026-55831 disclosed?
CVE-2026-55831 was first published in the National Vulnerability Database on July 20, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55831 actively exploited?
CVE-2026-55831 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 34.7% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-55831?
CVE-2026-55831 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-55831?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55831, 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-2026-55831
Is Your Infrastructure Affected by CVE-2026-55831?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.