{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-91134",
        "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "state": "PUBLISHED",
        "assignerShortName": "GitHub_M",
        "dateReserved": "2026-09-14T19:36:48.844Z",
        "datePublished": "2026-09-24T16:51:34.057Z",
        "dateUpdated": "2026-09-29T02:56:30.376Z"
    },
    "containers": {
        "cna": {
            "title": "Discourse: Block post iframes whose encoded userinfo bypasses the allowed_iframes allowlist",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-20",
                            "lang": "en",
                            "description": "CWE-20: Improper Input Validation",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV3_1": {
                        "attackComplexity": "LOW",
                        "attackVector": "NETWORK",
                        "availabilityImpact": "NONE",
                        "baseScore": 5.4,
                        "baseSeverity": "MEDIUM",
                        "confidentialityImpact": "LOW",
                        "integrityImpact": "LOW",
                        "privilegesRequired": "LOW",
                        "scope": "UNCHANGED",
                        "userInteraction": "NONE",
                        "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
                        "version": "3.1"
                    }
                }
            ],
            "references": [
                {
                    "name": "https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpv",
                    "tags": [
                        "x_refsource_CONFIRM"
                    ],
                    "url": "https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpv"
                },
                {
                    "name": "https://github.com/discourse/discourse/pull/42882",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/discourse/discourse/pull/42882"
                },
                {
                    "name": "https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415"
                },
                {
                    "name": "https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590"
                },
                {
                    "name": "https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309d",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309d"
                },
                {
                    "name": "https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64",
                    "tags": [
                        "x_refsource_MISC"
                    ],
                    "url": "https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64"
                }
            ],
            "affected": [
                {
                    "vendor": "discourse",
                    "product": "discourse",
                    "versions": [
                        {
                            "version": "< 2026.8.0",
                            "status": "affected"
                        },
                        {
                            "version": ">= 2026.7.0-latest, < 2026.7.2",
                            "status": "affected"
                        },
                        {
                            "version": ">= 2026.6.0-latest, < 2026.6.3",
                            "status": "affected"
                        },
                        {
                            "version": ">= 2026.1.0-latest, < 2026.1.8",
                            "status": "affected"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
                "shortName": "GitHub_M",
                "dateUpdated": "2026-09-24T16:51:34.057Z"
            },
            "descriptions": [
                {
                    "lang": "en",
                    "value": "Discourse is an open-source discussion platform. Prior to 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0, the Discourse post sanitizer allowed a stored cross-origin iframe to bypass the allowed_iframes prefix policy when the iframe src contained encoded userinfo. The sanitizer validated a decoded form differently from the stored iframe src, allowing the browser to interpret an attacker-controlled host while the allowlist check accepted the encoded URL as an allowed prefix. An authenticated user with posting privileges could persist the iframe in a post and cause attacker-controlled cross-origin content to be rendered. This issue is fixed in versions 2026.1.8, 2026.6.3, 2026.7.2, and 2026.8.0."
                }
            ],
            "source": {
                "advisory": "GHSA-54vw-chv3-wjpv",
                "discovery": "UNKNOWN"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-09-29T02:56:20.350456Z",
                                "id": "CVE-2026-91134",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-09-29T02:56:30.376Z"
                }
            }
        ]
    }
}