CVE-2026-91134

{"id": "CVE-2026-91134", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-91134", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-09-29T02:56:20.350456Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.4, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "LOW"}, "impactScore": 2.5, "exploitabilityScore": 2.8}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "discourse", "product": "discourse", "versions": [{"status": "affected", "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"}]}]}], "published": "2026-09-24T17:17:09.080", "references": [{"url": "https://github.com/discourse/discourse/commit/0a8015e6c7a5079981843721494d30c9a91f5415", "source": "security-advisories@github.com"}, {"url": "https://github.com/discourse/discourse/commit/1304b0c04f87534053b0d574ae5a9b9ba13dd590", "source": "security-advisories@github.com"}, {"url": "https://github.com/discourse/discourse/commit/bac7dd1201911851462483271b4567246fa1309d", "source": "security-advisories@github.com"}, {"url": "https://github.com/discourse/discourse/commit/fed3a58c48412ce7207b72a4629ddbc44482cd64", "source": "security-advisories@github.com"}, {"url": "https://github.com/discourse/discourse/pull/42882", "source": "security-advisories@github.com"}, {"url": "https://github.com/discourse/discourse/security/advisories/GHSA-54vw-chv3-wjpv", "source": "security-advisories@github.com"}], "vulnStatus": "Deferred", "weaknesses": [{"type": "Secondary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-20"}]}], "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."}], "lastModified": "2026-09-29T03:17:21.580", "sourceIdentifier": "security-advisories@github.com"}