CVE-2026-33228

CRITICALNVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.8 under NVD CVSS v3. EPSS exploit probability: 0.8%, top 46% 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: 1%CVSS: 9.8Exploit: Elevated riskExposed: 0

A fix is available — apply it.

flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key "__proto__" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2.

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
55%
KEV
Not listed

Published

March 20, 2026

Last Modified

September 7, 2026

Advisory Details (8)

Auto-updated Sep 14, 2026
Patch available. Sources: github, github_commit.
github_commit

commit 885ddcc33cf9 (WebReflection/flatted)

Fix landed in WebReflection/flatted commit 885ddcc33cf9 — awaiting tagged release

https://github.com/WebReflection/flatted/commit/885ddcc33cf9657caf38c57c7be45ae1c5272802
github Patch Available

Prototype Pollution via parse() in NodeJS flatted (CWE-1321) · Advisory · WebReflection/flatted · GitHub

https://github.com/WebReflection/flatted/security/advisories/GHSA-rf6f-7fwh-wjgh
redhat Patch Available

Affected: Red Hat Enterprise Linux 10",

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33228.json
redhat Patch Available

2449872 – (CVE-2026-33228) CVE-2026-33228 flatted: Flatted: Prototype pollution vulnerability allows arbitrary code execution via crafted JSON.

https://bugzilla.redhat.com/show_bug.cgi?id=2449872
redhat Patch Available

CVE-2026-33228 - 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-2026-33228
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:9742
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:34342
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:13826

Vendor Advisories for CVE-2026-33228(4)

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 / EcosystemFixed in / PatchReleasedSource
redhatcluster-observability-operator/troubleshooting-panel-console-plugin-pf6-rhel9:17828399962026-07-01redhat
redhatrhdh/rhdh-hub-rhel9:17779032622026-05-05redhat
redhatrhdh/rhdh-hub-rhel9:17767842862026-04-22redhat

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
node-flatted2.0.2~dfsg-1 ... 3.4.2~ds-1 (14 versions)——
Debian:12(1)
PackageVulnerable rangeFixed inDependents
node-flatted3.2.7~ds-1, 3.2.7~ds-1+deb12u1, 3.4.1~ds-1, 3.4.2~ds-1, 3.4.4~ds-1——
Debian:13(1)
PackageVulnerable rangeFixed inDependents
node-flatted3.2.7~ds-13.2.7~ds-1+deb13u1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
node-flatted3.2.7~ds-1, 3.4.1~ds-13.4.2~ds-1—
npm(1)
PackageVulnerable rangeFixed inDependents
flatted—3.4.2—

Weakness Classification(2)

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

Data Freshness Timeline

(refreshed 8× in last 7d / 38× 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 158 total refreshes for this CVE.

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

Frequently asked(5)

What is CVE-2026-33228?
CVE-2026-33228 is a critical vulnerability published on March 20, 2026. flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with…
When was CVE-2026-33228 disclosed?
CVE-2026-33228 was first published in the National Vulnerability Database on March 20, 2026, with the most recent update on September 7, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33228 actively exploited?
CVE-2026-33228 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 44.7% of all scored CVEs.
What is the CVSS score of CVE-2026-33228?
CVE-2026-33228 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-33228?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33228, 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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