CVE-2026-59903

HIGHNVD 7.57.5
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to NVD's CVSS score.

This high-severity CVE scores 7.5 under NVD CVSS v3. EPSS exploit probability: 0.3% (25th percentile of EPSS-scored CVEs). GitHub Security Advisory CVSS 6.5 is lower than this score; a lower GitHub score revises it only when its advisory is newer than the CVE record's last change, and this advisory (published 2026-08-17) is not newer than that change (2026-09-23), so it does not.

Triggered by: Headline CVSS from NVD CVSS v3
Sources: EPSS, GitHub Security Advisory, NVD CVSS v3
Trending — 4 sources updated this week

Also known asEUVD-2026-60318 (ENISA EUVD) · GHSA-8c42-7qj2-3j46 (GitHub Security Advisories)Source: ENISA EUVD

7.5EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.3%CVSS: 7.5Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, io.netty.handler.codec.http.cors.CorsHandler setVaryHeader replaces application Vary headers such as Authorization or Cookie with Origin, allowing a caching proxy or CDN to reuse authenticated responses across users and disclose sensitive information. This issue is fixed in versions 4.1.137.Final and 4.2.17.Final.

CVSS v3
7.5
EG Score
7.5HIGHmedium confidence
EG Risk
34
EG Risk 34/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity75% × 45%
Impact severity (EG Severity): CVSS 7.5 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.3% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability0% × 15%
CISA's SSVC Automatable value: no (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.3%
EPSS %ILE
25th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (7.5): severity, escalated by confirmed exploitation. This CVE's 7.5 is its impact severity (EG Severity), not escalated.

EG Severity
7.5 HIGHCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.NVD CVSS v3 · CVSS v3.0 or v3.1
EG Likelihood
0.3% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-31). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.

A fix is available. Apply it within your standard update timelines.

Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.

The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

August 17, 2026

Last Modified

September 23, 2026

Advisory Details (5)

Auto-updated Aug 17, 2026
Patch available. Sources: github, github_pr, github_release.
GitHub release Patch Available

netty-4.2.17.Final

Patch available: netty/netty netty-4.2.17.Final

https://github.com/netty/netty/releases/tag/netty-4.2.17.Final
GitHub release Patch Available

netty-4.1.137.Final

Patch available: netty/netty netty-4.1.137.Final

https://github.com/netty/netty/releases/tag/netty-4.1.137.Final
GitHub pull request Patch Available

Merge changes from forks (#17213)

Patch available: netty/netty netty-4.1.137.Final (PR #17217 merged 2026-08-06)

https://github.com/netty/netty/pull/17217
GitHub pull request Patch Available

Merge changes from forks

Patch available: netty/netty netty-4.2.17.Final (PR #17213 merged 2026-08-04)

https://github.com/netty/netty/pull/17213
GitHub advisoryMentions a patch (unverified)

Cache Poisoning and Information Disclosure via CORS Vary Header Overwrite · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-8c42-7qj2-3j46

Vendor Advisories for CVE-2026-59903(7)

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

Patch Availability(3)

Vendor / EcosystemFix (by version range) / PatchReleasedSource
redhatio.netty/netty-codec-http:4.1.137.Final-redhat-000012026-09-03redhat
mavenio.netty:netty-codec-http @ 4.2.17.Final (fixes >= 4.2.0.Final, <= 4.2.16.Final)—ghsa
mavenio.netty:netty-codec-http @ 4.1.137.Final (fixes <= 4.1.136.Final)—ghsa

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

(4 across 4 ecosystems)
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 (230 versions)
  • 4.2.0.Final up to 4.2.17.Final: fixed in 4.2.17.Final
  • every version up to 4.1.137.Final: fixed in 4.1.137.Final
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 11× in last 7d / 47× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 132 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 32 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-11-01 16:35 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  2. 2026-11-01 07:41 UTCEG score recompute
  3. 2026-11-01 07:41 UTCGHSA enrichmentGHSA-8c42-7qj2-3j46 · GitHub severity MODERATE · GitHub CVSS 6.5
  4. 2026-10-31 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  5. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  6. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  7. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  8. 2026-10-27 19:18 UTCEG score recompute
  9. 2026-10-27 19:18 UTCVendor advisory
  10. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  11. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  12. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.3% · 25th percentile
  13. 2026-10-25 14:16 UTCEG score recompute
  14. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  15. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  16. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  17. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  18. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  19. 2026-10-20 09:37 UTCEG score recompute
  20. 2026-10-20 09:37 UTCVendor advisory
  21. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  22. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  23. 2026-10-18 03:27 UTCEG score recompute
  24. 2026-10-17 16:35 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  25. 2026-10-16 16:43 UTCEPSS rescoreEPSS 0.2% · 14th percentile
Show 75 more
  1. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  2. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  3. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  4. 2026-10-13 15:48 UTCEG score recompute
  5. 2026-10-13 15:48 UTCVendor advisory
  6. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  7. 2026-10-12 15:52 UTCEG score recompute
  8. 2026-10-11 19:36 UTCEG score recompute
  9. 2026-10-11 16:51 UTCEG score recompute
  10. 2026-10-11 14:13 UTCEG score recompute
  11. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  12. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  13. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  14. 2026-10-08 17:13 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  15. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  16. 2026-10-06 21:44 UTCEG score recompute
  17. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  18. 2026-10-06 09:02 UTCEG score recompute
  19. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  20. 2026-10-05 06:38 UTCEG score recompute
  21. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  22. 2026-10-03 17:47 UTCEG score recompute
  23. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  24. 2026-10-03 02:34 UTCEG score recompute
  25. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  26. 2026-10-02 01:34 UTCEG score recompute
  27. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  28. 2026-09-30 20:52 UTCEG score recompute
  29. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  30. 2026-09-30 09:59 UTCEG score recompute
  31. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  32. 2026-09-28 21:59 UTCEG score recompute
  33. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  34. 2026-09-27 18:54 UTCEG score recompute
  35. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  36. 2026-09-27 08:05 UTCEG score recompute
  37. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  38. 2026-09-25 02:01 UTCEG score recompute
  39. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.2% · 14th percentile
  40. 2026-09-24 02:26 UTCEG score recompute
  41. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  42. 2026-09-23 15:38 UTCEG score recompute▲ 1.00
  43. 2026-09-23 15:36 UTCNVD updateCVSS v3 → 7.5 · severity → HIGH
  44. 2026-09-22 23:47 UTCEG score recompute
  45. 2026-09-21 23:44 UTCEG score recompute
  46. 2026-09-20 23:53 UTCEG score recompute
  47. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  48. 2026-09-20 00:01 UTCEG score recompute
  49. 2026-09-19 00:10 UTCEG score recompute
  50. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.2% · 16th percentile
  51. 2026-09-18 00:18 UTCEG score recompute
  52. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  53. 2026-09-16 23:07 UTCEG score recompute
  54. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  55. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  56. 2026-09-15 21:27 UTCEG score recompute
  57. 2026-09-15 03:11 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  58. 2026-09-13 20:32 UTCEG score recompute
  59. 2026-09-13 16:47 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  60. 2026-09-12 20:41 UTCEG score recompute
  61. 2026-09-11 20:51 UTCEG score recompute
  62. 2026-09-11 14:53 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  63. 2026-09-10 20:59 UTCEG score recompute
  64. 2026-09-10 09:35 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  65. 2026-09-09 05:35 UTCEG score recompute
  66. 2026-09-08 22:01 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  67. 2026-09-08 05:44 UTCEG score recompute
  68. 2026-09-07 16:01 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  69. 2026-09-07 05:32 UTCEG score recompute
  70. 2026-09-06 13:47 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  71. 2026-09-06 05:28 UTCEG score recompute
  72. 2026-09-05 05:38 UTCEG score recompute
  73. 2026-09-04 05:48 UTCEG score recompute
  74. 2026-09-04 05:07 UTCEPSS rescoreEPSS 0.2% · 15th percentile
  75. 2026-09-03 05:49 UTCEG score recompute

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

Frequently asked(5)

What is CVE-2026-59903?
CVE-2026-59903 is a high-severity vulnerability; its CVE record was published on August 17, 2026. Netty is an asynchronous, event-driven network application framework. Prior to 4.1.137.Final and 4.2.17.Final, io.netty.handler.codec.http.cors.CorsHandler setVaryHeader replaces application Vary headers such as Authorization or Cookie with Origin, allowing a caching proxy or CDN to reuse…
When was the CVE record for CVE-2026-59903 published?
The CVE record for CVE-2026-59903 was published on August 17, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 23, 2026; the record at its source may have been updated since.
Is CVE-2026-59903 actively exploited?
CVE-2026-59903 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.3% probability of exploitation in the next 30 days (25th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-59903?
CVE-2026-59903 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-59903?
A fix for CVE-2026-59903 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-59903 are linked in the Vendor Advisories panel on this page.

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