CVE-2026-42581

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 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 — 3 sources updated this weekElevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 9.8Exploit: Elevated riskExposed: 0

A fix is available — apply it.

Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent for HTTP/1.0. An attacker that sends an HTTP/1.0 request with both headers causes Netty to decode the body as chunked while leaving Content-Length intact in the forwarded HttpMessage. Any downstream proxy or handler that trusts Content-Length over Transfer-Encoding will disagree on message boundaries, enabling request smuggling. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

CVSS v3
9.8
EG Score
9.8(medium)
EG Risk
75(Attend)
EG Risk 75/100SSVC: Attend

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
Severity98% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS PROB
1%
EPSS %ILE
48%
KEV
Not listed

Published

May 13, 2026

Last Modified

August 21, 2026

Advisory Details (13)

Auto-updated Aug 21, 2026
🔬 Proof of concept available. Patch available. Sources: github, redhat.
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:53806
redhat Patch Available

Affected: Red Hat Enterprise Linux 7. Red Hat Product Security has rated

https://access.redhat.com/errata/RHSA-2026:53644
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:42644
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:37390
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:36820
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:28010
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:25123
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:24502
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:23808
github Patch Available🟡 PoC Available

HTTP/1.0 TE+CL Coexistence Bypasses Smuggling Sanitization · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-xxqh-mfjm-7mv9
redhat Patch Available

2477232 – (CVE-2026-42581) CVE-2026-42581 netty: io.netty/netty-codec-http: Netty: HTTP Request Smuggling due to improper handling of conflicting HTTP/1.0 headers

https://bugzilla.redhat.com/show_bug.cgi?id=2477232
redhat Patch Available

CVE-2026-42581 - Red Hat Customer Portal

Affected: Red Hat Enterprise Linux 8 or OpenShift Container Platform 4, is affected by this vulnerability and a fix may be released to a

https://access.redhat.com/security/cve/CVE-2026-42581
redhat Patch Available
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42581.json

Vendor Advisories for CVE-2026-42581(10)

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

Patch Availability(8)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibnetty-java (1:4.1.7-4ubuntu0.1+esm6) @ bionic2026-08-23ubuntu
redhatnetty-codec-http2026-08-12redhat
redhateap7-wildfly-0:7.4.25-2.GA_redhat_00001.1.el7eap2026-08-11redhat
redhatrhoai/odh-modelmesh-rhel9:17834438162026-07-21redhat
redhatdevspaces/multicluster-redirector-rhel9:17829890272026-07-08redhat
redhatcryostat/jfr-datasource-rhel9:4.2.0-102026-06-22redhat
redhatpatch2026-06-10redhat
redhatdevspaces/server-rhel9:17806949942026-06-10redhat

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-http4.0.0.Alpha1 ... 4.1.99.Final (226 versions)4.1.133.Final—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 15× in last 7d / 119× 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 224 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-42581?
CVE-2026-42581 is a critical vulnerability published on May 13, 2026. Netty is an asynchronous, event-driven network application framework. Prior to 4.2.13.Final and 4.1.133.Final, HttpObjectDecoder strips a conflicting Content-Length header when a request carries both Transfer-Encoding: chunked and Content-Length, but only for HTTP/1.1 messages. The guard is absent…
When was CVE-2026-42581 disclosed?
CVE-2026-42581 was first published in the National Vulnerability Database on May 13, 2026, with the most recent update on August 21, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42581 actively exploited?
CVE-2026-42581 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 52.5% of all scored CVEs.
What is the CVSS score of CVE-2026-42581?
CVE-2026-42581 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-42581?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42581, 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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