{
    "CVE_data_meta": {
        "ASSIGNER": "security-advisories@github.com",
        "ID": "CVE-2021-41115",
        "STATE": "PUBLIC",
        "TITLE": "Regular expression denial-of-service in Zulip"
    },
    "affects": {
        "vendor": {
            "vendor_data": [
                {
                    "product": {
                        "product_data": [
                            {
                                "product_name": "zulip",
                                "version": {
                                    "version_data": [
                                        {
                                            "version_value": "< 4.7"
                                        }
                                    ]
                                }
                            }
                        ]
                    },
                    "vendor_name": "zulip"
                }
            ]
        }
    },
    "data_format": "MITRE",
    "data_type": "CVE",
    "data_version": "4.0",
    "description": {
        "description_data": [
            {
                "lang": "eng",
                "value": "Zulip is an open source team chat server. In affected versions Zulip allows organization administrators on a server to configure \"linkifiers\" that automatically create links from messages that users send, detected via arbitrary regular expressions. Malicious organization administrators could subject the server to a denial-of-service via regular expression complexity attacks; most simply, by configuring a quadratic-time regular expression in a linkifier, and sending messages that exploited it. A regular expression attempted to parse the user-provided regexes to verify that they were safe from ReDoS -- this was both insufficient, as well as _itself_ subject to ReDoS if the organization administrator entered a sufficiently complex invalid regex. Affected users should [upgrade to the just-released Zulip 4.7](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-to-a-release), or [`main`](https://zulip.readthedocs.io/en/latest/production/upgrade-or-modify.html#upgrading-from-a-git-repository)."
            }
        ]
    },
    "impact": {
        "cvss": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 4.3,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "LOW",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L",
            "version": "3.1"
        }
    },
    "problemtype": {
        "problemtype_data": [
            {
                "description": [
                    {
                        "lang": "eng",
                        "value": "CWE-400: Uncontrolled Resource Consumption"
                    }
                ]
            },
            {
                "description": [
                    {
                        "lang": "eng",
                        "value": "CWE-1333: Inefficient Regular Expression Complexity"
                    }
                ]
            }
        ]
    },
    "references": {
        "reference_data": [
            {
                "name": "https://github.com/zulip/zulip/security/advisories/GHSA-4h36-mqfq-42jg",
                "refsource": "CONFIRM",
                "url": "https://github.com/zulip/zulip/security/advisories/GHSA-4h36-mqfq-42jg"
            },
            {
                "name": "https://github.com/zulip/zulip/commit/e2d303c1bb5f538d17dc3d9134bc8858bdece781",
                "refsource": "MISC",
                "url": "https://github.com/zulip/zulip/commit/e2d303c1bb5f538d17dc3d9134bc8858bdece781"
            },
            {
                "name": "https://securitylab.github.com/advisories/GHSL-2021-118-zulip-zulip/",
                "refsource": "MISC",
                "url": "https://securitylab.github.com/advisories/GHSL-2021-118-zulip-zulip/"
            }
        ]
    },
    "source": {
        "advisory": "GHSA-4h36-mqfq-42jg",
        "discovery": "UNKNOWN"
    }
}