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 51% 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
Elevated
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.7%CVSS: 9.8Exploit: Elevated riskExposed services: Not assessed

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
9.8CRITICALmedium confidence
EG Risk
75
EG Risk 75/100

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%
EPSS PROB
0.7%
EPSS %ILE
51st
KEV
Not listed

Published

May 13, 2026

Last Modified

September 18, 2026

Advisory Details (15)

Auto-updated Oct 9, 2026
🔬 Proof of concept available. Patch available. Sources: github, redhat.
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:49701
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:49700
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:42644
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:37390
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:36820
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:28010
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:25123
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:24502
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:23808
githubMentions a patch (unverified)🟡 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
redhatMentions a patch (unverified)

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

https://access.redhat.com/errata/RHSA-2026:53644
redhatMentions a patch (unverified)
https://access.redhat.com/errata/RHSA-2026:53806
redhatMentions a patch (unverified)

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
redhatMentions a patch (unverified)

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
redhatMentions a patch (unverified)
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42581.json

Vendor Advisories for CVE-2026-42581(20)

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

Patch Availability(13)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
ubuntulibnetty-java (1:4.1.45-1ubuntu0.1~esm6) @ focal2026-09-18ubuntu
redhatnetty-codec-http2026-09-10redhat
redhatrhoai/odh-trustyai-service-rhel9:17881986812026-09-08redhat
redhateap7-wildfly-0:7.4.25-2.GA_redhat_00001.1.el8eap2026-08-11redhat
redhateap7-wildfly-0:7.4.25-2.GA_redhat_00001.1.el9eap2026-08-11redhat
redhateap7-wildfly-0:7.4.25-2.GA_redhat_00001.1.el7eap2026-08-11redhat
redhatio.netty/netty-codec-http:4.1.135.Final-redhat-000012026-08-03redhat
redhateap8-wildfly-0:8.1.7.1-1.GA_redhat_00004.1.el9eap2026-08-03redhat
redhatrhoai/odh-modelmesh-rhel9:17834438162026-07-21redhat
redhatdevspaces/multicluster-redirector-rhel9:17829890272026-07-08redhat
redhatcryostat/jfr-datasource-rhel9:4.2.0-102026-06-22redhat
redhatdevspaces/server-rhel9:17806949942026-06-10redhat
redhatpatch2026-06-10redhat

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 rangeFix by version rangeDependents
netty1:4.1.48-10 ... 1:4.1.48-9 (16 versions)
  • every version on: no fix on record
—
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.48-10 ... 1:4.1.48-9 (12 versions)
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.48-10 ... 1:4.1.48-16 (8 versions)
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
netty1:4.1.48-10 ... 1:4.1.48-16 (7 versions)
  • every version on: no fix on record
—
Maven(1)
PackageVulnerable rangeFix by version rangeDependents
io.netty:netty-codec-http4.0.0.Alpha1 ... 4.1.99.Final (226 versions)
  • 4.2.0.Alpha1 up to 4.2.13.Final: fixed in 4.2.13.Final
  • every version up to 4.1.133.Final: fixed in 4.1.133.Final
—

Weakness Classification(1)

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

Additional Vendor Advisories

(6)

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 8× in last 7d / 32× 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 278 total refreshes for this CVE.

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

Related CVEs(same product + same vendor + same CWE)

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 on May 13, 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-2026-42581 actively exploited?
CVE-2026-42581 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.7% probability of exploitation in the next 30 days (51st percentile of EPSS-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?
A fix for CVE-2026-42581 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-42581 are linked in the Vendor Advisories panel on this page.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-42581

Explore →

Is Your Infrastructure Affected by CVE-2026-42581?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Book a Demo →Browse All CVEs