CVE-2026-89044

MEDIUMPre-NVD 6.56.5—
EchelonGraph scoreHIGH confidence

Score 6.5 from GitHub Security Advisory published 2026-09-10. a secondary CVSS source baseline 6.5; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, secondary
Trending — 3 sources updated this week
6.5EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0%CVSS: 6.5Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Netty versions 4.1.133.Final through 4.1.137.Final and 4.2.13.Final through 4.2.17.Final fail to properly validate the final transfer coding in the Transfer-Encoding header, allowing attackers to smuggle requests by using malformed encoding declarations. Attackers can split Transfer-Encoding headers across multiple lines or use values like 'chunked, xchunked' to bypass validation and decode messages as chunked when the final coding is not chunked, enabling request smuggling attacks.

CVSS v3
6.5
EG Score
6.5(high)
EG Risk
44(Track)
EG Risk 44/100SSVC: 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
Severity65% × 45%
Exploitation0% × 40%
Automatability100% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
0%
EPSS %ILE
16%
KEV
Not listed

Published

September 10, 2026

Last Modified

September 18, 2026

Advisory Details (8)

Auto-updated Sep 10, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
generic

Netty 4.1.133.Final through 4.1.137.Final and 4.2.13.Final through 4.2.17.Final HTTP Request Smuggling via Transfer-Encoding | Advisories | VulnCheck

https://www.vulncheck.com/advisories/netty-4.1.133-final-through-4.1.137-final-and-4.2.13-final-through-4.2.17-final-http-request-smuggling-via-transfer-encoding
generic

GitHub - netty/netty: Netty project - an event-driven asynchronous network application framework · GitHub

https://github.com/netty/netty
github_release Patch Available

netty-4.2.18.Final

Patch available: netty/netty netty-4.2.18.Final

https://github.com/netty/netty/releases/tag/netty-4.2.18.Final
github_release Patch Available

netty-4.1.138.Final

Patch available: netty/netty netty-4.1.138.Final

https://github.com/netty/netty/releases/tag/netty-4.1.138.Final
generic

netty/codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectDecoder.java at netty-4.1.137.Final · netty/netty · GitHub

https://github.com/netty/netty/blob/netty-4.1.137.Final/codec-http/src/main/java/io/netty/handler/codec/http/HttpObjectDecoder.java#L866
github_commit Patch Available

commit 640d4d3324f7 (netty/netty)

Patch available: netty/netty netty-4.2.18.Final (contains commit 640d4d3324f7)

https://github.com/netty/netty/commit/640d4d3324f7b811a4903d0730c8ccb35500500c
github_commit Patch Available

commit ca87393b0e9e (netty/netty)

Patch available: netty/netty netty-4.1.138.Final (contains commit ca87393b0e9e)

https://github.com/netty/netty/commit/ca87393b0e9e13c493d213a268e727a6d44e1585
github Patch Available🟡 PoC Available

Incomplete validation of malformed Transfer-Encoding allows HTTP request smuggling · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-hcvj-94mj-jp5c

Vendor Advisories for CVE-2026-89044(1)

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

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 21× in last 7d / 31× 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. 2026-09-18 19:28 UTCEPSS rescore
  2. 2026-09-18 18:33 UTCEG score recompute
  3. 2026-09-18 18:33 UTCGHSA enrichment
  4. 2026-09-18 17:29 UTCEG score recompute
  5. 2026-09-18 17:29 UTCGHSA enrichment
  6. 2026-09-17 19:46 UTCEG score recompute
  7. 2026-09-17 19:46 UTCGHSA enrichment
  8. 2026-09-17 19:32 UTCEPSS rescore
  9. 2026-09-16 16:06 UTCEG score recompute
  10. 2026-09-16 16:06 UTCGHSA enrichment
  11. 2026-09-16 14:09 UTCEPSS rescore
  12. 2026-09-16 05:15 UTCEPSS rescore
  13. 2026-09-16 05:14 UTCGHSA enrichment
  14. 2026-09-15 03:23 UTCEG score recompute
  15. 2026-09-15 03:23 UTCGHSA enrichment
  16. 2026-09-15 03:12 UTCEPSS rescore
  17. 2026-09-14 01:32 UTCEG score recompute
  18. 2026-09-14 01:32 UTCGHSA enrichment
  19. 2026-09-13 16:48 UTCEPSS rescore
  20. 2026-09-12 23:41 UTCEG score recompute
  21. 2026-09-12 23:41 UTCGHSA enrichment
  22. 2026-09-12 15:02 UTCEPSS rescore
  23. 2026-09-11 21:50 UTCEG score recompute
  24. 2026-09-11 21:50 UTCGHSA enrichment
  25. 2026-09-11 14:53 UTCEPSS rescore
Show 6 more
  1. 2026-09-11 14:53 UTCEPSS rescore
  2. 2026-09-10 19:58 UTCEG score recompute
  3. 2026-09-10 19:58 UTCGHSA enrichment
  4. 2026-09-10 18:22 UTCEG score recompute
  5. 2026-09-10 17:45 UTCEG score recompute
  6. 2026-09-10 17:44 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-89044?
CVE-2026-89044 is a medium vulnerability published on September 10, 2026. Netty versions 4.1.133.Final through 4.1.137.Final and 4.2.13.Final through 4.2.17.Final fail to properly validate the final transfer coding in the Transfer-Encoding header, allowing attackers to smuggle requests by using malformed encoding declarations. Attackers can split Transfer-Encoding…
When was CVE-2026-89044 disclosed?
CVE-2026-89044 was first published in the National Vulnerability Database on September 10, 2026, with the most recent update on September 18, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-89044 actively exploited?
CVE-2026-89044 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 84.2% of all scored CVEs.
What is the CVSS score of CVE-2026-89044?
CVE-2026-89044 has a CVSS v3 base score of 6.5 (NVD).
How do I remediate CVE-2026-89044?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-89044, 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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