{ "document": { "category": "csaf_base", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings." } ], "publisher": { "category": "coordinator", "contact_details": "cert@ncsc.nl", "name": "National Cyber Security Centre", "namespace": "https://www.ncsc.nl/" }, "title": "CVE-2026-33228", "tracking": { "current_release_date": "2026-03-29T16:14:25.083928Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-33228", "initial_release_date": "2026-03-20T18:15:32.840281Z", "revision_history": [ { "date": "2026-03-20T18:15:32.840281Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (1).| CWES updated (1)." }, { "date": "2026-03-20T18:15:37.961079Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-20T18:16:26.322125Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-20T18:16:30.470914Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-20T23:25:45.706109Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)." }, { "date": "2026-03-20T23:25:52.673900Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-03-20T23:39:27.554711Z", "number": "7", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (3).| CWES updated (1)." }, { "date": "2026-03-20T23:39:31.513179Z", "number": "8", "summary": "NCSC Score updated." }, { "date": "2026-03-21T07:40:43.812208Z", "number": "9", "summary": "NCSC Score updated." }, { "date": "2026-03-21T12:44:16.926013Z", "number": "10", "summary": "Source created.| CVE status created. (valid)| Description created for source.| Products connected (2)." }, { "date": "2026-03-21T12:44:18.910018Z", "number": "11", "summary": "NCSC Score updated." }, { "date": "2026-03-21T15:23:06.922544Z", "number": "12", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-24T13:49:18.461171Z", "number": "13", "summary": "CVSS created.| Products created (1).| Product Identifiers created (1).| Exploits created (1)." }, { "date": "2026-03-24T13:49:20.370612Z", "number": "14", "summary": "NCSC Score updated." }, { "date": "2026-03-24T20:56:26.923796Z", "number": "15", "summary": "Unknown change." }, { "date": "2026-03-24T20:57:25.602838Z", "number": "16", "summary": "NCSC Score updated." }, { "date": "2026-03-25T12:20:14.316589Z", "number": "17", "summary": "Source connected.| CVE status created. (valid)| Description created for source.| Products connected (2).| CWES updated (1)." }, { "date": "2026-03-25T12:20:16.901107Z", "number": "18", "summary": "NCSC Score updated." }, { "date": "2026-03-25T18:41:55.839550Z", "number": "19", "summary": "References created (3)." }, { "date": "2026-03-25T18:42:08.945273Z", "number": "20", "summary": "NCSC Score updated." }, { "date": "2026-03-26T00:21:20.812768Z", "number": "21", "summary": "References created (3)." }, { "date": "2026-03-29T03:16:13.715684Z", "number": "22", "summary": "References removed (3)." }, { "date": "2026-03-29T03:16:18.324022Z", "number": "23", "summary": "NCSC Score updated." }, { "date": "2026-03-29T16:14:20.013194Z", "number": "24", "summary": "References created (3)." } ], "status": "interim", "version": "24" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:microsoft/*", "product": { "name": "vers:microsoft/*", "product_id": "CSAFPID-5197899", "product_identification_helper": { "cpe": "cpe:2.3:a:microsoft:azl3_python-tensorboard_2.16.2-6:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "azl3 python-tensorboard 2.16.2-6 on Azure Linux 3.0" }, { "branches": [ { "category": "product_version_range", "name": "vers:microsoft/*", "product": { "name": "vers:microsoft/*", "product_id": "CSAFPID-5202168", "product_identification_helper": { "cpe": "cpe:2.3:a:microsoft:cbl2_python-tensorboard_2.11.0-3:*:*:*:*:*:*:*:*" } } } ], "category": "product_name", "name": "cbl2 python-tensorboard 2.11.0-3 on CBL Mariner 2.0" } ], "category": "product_family", "name": "Open Source Software" } ], "category": "vendor", "name": "Microsoft" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<3.4.2", "product": { "name": "vers:unknown/<3.4.2", "product_id": "CSAFPID-5878175" } }, { "category": "product_version_range", "name": "vers:unknown/>=0|<3.4.2", "product": { "name": "vers:unknown/>=0|<3.4.2", "product_id": "CSAFPID-5873803" } } ], "category": "product_name", "name": "flatted" } ], "category": "vendor", "name": "WebReflection" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<3.4.2", "product": { "name": "vers:unknown/<3.4.2", "product_id": "CSAFPID-5899393", "product_identification_helper": { "cpe": "cpe:2.3:a:webreflection:flatted:*:*:*:*:*:node.js:*:*" } } } ], "category": "product_name", "name": "flatted" } ], "category": "vendor", "name": "webreflection" }, { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-5827441" } } ], "category": "product_name", "name": "node-flatted" } ], "category": "product_family", "name": "bookworm" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-5827442" } } ], "category": "product_name", "name": "node-flatted" } ], "category": "product_family", "name": "bullseye" } ], "category": "vendor", "name": "debian" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-33228", "cwe": { "id": "CWE-1321", "name": "Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')" }, "notes": [ { "category": "description", "text": "---\n **Summary**\n\n The parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index\n keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it\n with the key \"\\_\\_proto\\_\\_\" returns Array.prototype via the inherited getter. This object is then treated as a legitimate\n parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype\n to the consumer. Any code that subsequently writes to that property will pollute the global prototype.\n\n ---\n **Root Cause**\n\n File: esm/index.js:29 (identical in cjs/index.js)\n```\n const resolver = (input, lazy, parsed, $) => output => {\n for (let ke = keys(output), {length} = ke, y = 0; y < length; y++) {\n const k = ke[y];\n const value = output[k]; \n if (value instanceof Primitive) {\n const tmp = input[value]; // Bug is here\n```\n\nNo validation that value is a safe numeric index input is built as a plain Array. JavaScript's property lookup on arrays traverses the prototype chain for non-numeric keys. The key \"\\_\\_proto\\_\\_\" resolves to Array.prototype, which:\n\n - has type \"object\" → passes the typeof tmp === object guard at line 30\n - is not in the parsed Set yet → passes the !parsed.has(tmp) guard.\n - The reference to Array.prototype is then enqueued in lazy and later unconditionally assigned to the output object.\n ---\n **Replication Steps**\n```\n const Flatted = require('flatted'); \n const parsed = Flatted.parse('[{\"x\":\"__proto__\"}]');\n parsed.x.polluted = 'pwned';\n console.log([].polluted); // Returns true\n``` \n ---\n **Impact**\n An attacker can supply a crafted flatted string to parse() that causes the returned object to hold a live reference to Array.prototype, enabling any downstream code that writes to that property to pollute the global prototype chain, potentially causing denial of service or code execution.\n\n **Recommended solution**\n Validate that the index string represents an integer within the bounds of input before accessing it:\n\n // Before (vulnerable)\n const tmp = input[value];\n\n // After (safe)\n const idx = +value; // coerce boxed String → number\n const tmp = (Number.isInteger(idx) && idx >= 0 && idx < input.length)\n ? input[idx]\n : undefined;", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/npm%2FGHSA-rf6f-7fwh-wjgh.json?alt=media" }, { "category": "description", "text": "---\n **Summary**\n\n The parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index\n keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it\n with the key \"\\_\\_proto\\_\\_\" returns Array.prototype via the inherited getter. This object is then treated as a legitimate\n parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype\n to the consumer. Any code that subsequently writes to that property will pollute the global prototype.\n\n ---\n **Root Cause**\n\n File: esm/index.js:29 (identical in cjs/index.js)\n```\n const resolver = (input, lazy, parsed, $) => output => {\n for (let ke = keys(output), {length} = ke, y = 0; y < length; y++) {\n const k = ke[y];\n const value = output[k]; \n if (value instanceof Primitive) {\n const tmp = input[value]; // Bug is here\n```\n\nNo validation that value is a safe numeric index input is built as a plain Array. JavaScript's property lookup on arrays traverses the prototype chain for non-numeric keys. The key \"\\_\\_proto\\_\\_\" resolves to Array.prototype, which:\n\n - has type \"object\" → passes the typeof tmp === object guard at line 30\n - is not in the parsed Set yet → passes the !parsed.has(tmp) guard.\n - The reference to Array.prototype is then enqueued in lazy and later unconditionally assigned to the output object.\n ---\n **Replication Steps**\n```\n const Flatted = require('flatted'); \n const parsed = Flatted.parse('[{\"x\":\"__proto__\"}]');\n parsed.x.polluted = 'pwned';\n console.log([].polluted); // Returns true\n``` \n ---\n **Impact**\n An attacker can supply a crafted flatted string to parse() that causes the returned object to hold a live reference to Array.prototype, enabling any downstream code that writes to that property to pollute the global prototype chain, potentially causing denial of service or code execution.\n\n **Recommended solution**\n Validate that the index string represents an integer within the bounds of input before accessing it:\n\n // Before (vulnerable)\n const tmp = input[value];\n\n // After (safe)\n const idx = +value; // coerce boxed String → number\n const tmp = (Number.isInteger(idx) && idx >= 0 && idx < input.length)\n ? input[idx]\n : undefined;", "title": "github - https://api.github.com/advisories/GHSA-rf6f-7fwh-wjgh" }, { "category": "description", "text": "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.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33228" }, { "category": "description", "text": "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.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33228.json" }, { "category": "description", "text": "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.", "title": "debian - https://security-tracker.debian.org/tracker/CVE-2026-33228" }, { "category": "description", "text": "flatted: Prototype Pollution via parse()", "title": "microsoft - https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2026-Mar" }, { "category": "other", "text": "0.00014", "title": "EPSS" }, { "category": "other", "text": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P", "title": "CVSSV4" }, { "category": "other", "text": "8.9", "title": "CVSSV4 base score" }, { "category": "other", "text": "4.4", "title": "NCSC Score" }, { "category": "other", "text": "Is related to a product by vendor Debian, There is product data available from source Cveprojectv5", "title": "NCSC Score top increasing factors" }, { "category": "other", "text": "Exploit code publicly available, There is exploit data available from source Nvd, Is related to CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'))", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5873803", "CSAFPID-5878175", "CSAFPID-5827441", "CSAFPID-5827442", "CSAFPID-5899393", "CSAFPID-5197899", "CSAFPID-5202168" ] }, "references": [ { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/npm%2FGHSA-rf6f-7fwh-wjgh.json?alt=media" }, { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-rf6f-7fwh-wjgh" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-33228" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/33xxx/CVE-2026-33228.json" }, { "category": "external", "summary": "Source - debian", "url": "https://security-tracker.debian.org/tracker/CVE-2026-33228" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - microsoft", "url": "https://api.msrc.microsoft.com/cvrf/v3.0/cvrf/2026-Mar" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/WebReflection/flatted/security/advisories/GHSA-rf6f-7fwh-wjgh" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-rf6f-7fwh-wjgh" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/WebReflection/flatted/commit/885ddcc33cf9657caf38c57c7be45ae1c5272802" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd; osv", "url": "https://github.com/WebReflection/flatted/releases/tag/v3.4.2" }, { "category": "external", "summary": "Reference - github; osv", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33228" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "products": [ "CSAFPID-5197899", "CSAFPID-5202168", "CSAFPID-5827441", "CSAFPID-5827442", "CSAFPID-5873803", "CSAFPID-5878175", "CSAFPID-5899393" ] } ], "title": "CVE-2026-33228" } ] }