CVE-2026-42587

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under the CNA's CVSS (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 58% 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: cna:github_m, epss
Elevated
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.5Exploit: NoneExposed: 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, HttpContentDecompressor accepts a maxAllocation parameter to limit decompression buffer size and prevent decompression bomb attacks. This limit is correctly enforced for gzip and deflate encodings via ZlibDecoder, but is silently ignored when the content encoding is br (Brotli), zstd, or snappy. An attacker can bypass the configured decompression limit by sending a compressed payload with Content-Encoding: br instead of Content-Encoding: gzip, causing unbounded memory allocation and out-of-memory denial of service. The same vulnerability exists in DelegatingDecompressorFrameListener for HTTP/2 connections. This vulnerability is fixed in 4.2.13.Final and 4.1.133.Final.

CVSS v3
7.5
EG Score
7.5(medium)
EPSS
56.6%
KEV
Not listed

Published

May 13, 2026

Last Modified

July 22, 2026

Advisory Details (1)

Auto-updated May 13, 2026
🔬 Proof of concept available. Patch available. Sources: github.
github Patch Available🟡 PoC Available

HttpContentDecompressor maxAllocation bypass via Content-Encoding: br/zstd/snappy enables decompression bomb DoS · Advisory · netty/netty · GitHub

https://github.com/netty/netty/security/advisories/GHSA-f6hv-jmp6-3vwv

Vendor Advisories for CVE-2026-42587(9)

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

Patch Availability(4)

Vendor / EcosystemFixed in / PatchReleasedSource
redhatcryostat/jfr-datasource-rhel9:4.2.0-102026-06-22redhat
redhatnetty-codec-http22026-06-10redhat
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

(2 across 1 ecosystem)
Maven(2)
PackageVulnerable rangeFixed inDependents
io.netty:netty-codec-http4.0.0.Alpha1 ... 4.1.99.Final (226 versions)4.1.133.Final—
io.netty:netty-codec-http24.1.0.Beta4 ... 4.1.99.Final (145 versions)4.1.133.Final—

Weakness Classification(2)

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

Data Freshness Timeline

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

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Frequently asked(5)

What is CVE-2026-42587?
CVE-2026-42587 is a high 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, HttpContentDecompressor accepts a maxAllocation parameter to limit decompression buffer size and prevent decompression bomb attacks. This limit is correctly enforced for gzip and deflate…
When was CVE-2026-42587 disclosed?
CVE-2026-42587 was first published in the National Vulnerability Database on May 13, 2026, with the most recent update on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-42587 actively exploited?
CVE-2026-42587 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 56.6% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-42587?
CVE-2026-42587 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-42587?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-42587, 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.

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