{"id":"CVE-2026-77272","summary":"MCP Atlassian: Reflected XSS in OAuth Setup Callback Handler","details":"MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the OAuth error query parameter is passed to CallbackHandler._send_response in oauth_setup.py and interpolated into an HTML page without escaping. A crafted authorization callback can inject markup or script that executes in the browser of a user completing the OAuth flow. This issue is fixed in version 0.22.0.","aliases":["GHSA-g2r2-3j32-j27x"],"modified":"2026-09-23T03:46:50.893382270Z","published":"2026-09-22T18:33:18.421Z","database_specific":{"cwe_ids":["CWE-79"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77272.json","cna_assigner":"GitHub_M"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77272.json"},{"type":"FIX","url":"https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460"},{"type":"FIX","url":"https://github.com/sooperset/mcp-atlassian/pull/1448"},{"type":"WEB","url":"https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0"},{"type":"ADVISORY","url":"https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g2r2-3j32-j27x"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-77272"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/sooperset/mcp-atlassian","events":[{"introduced":"0"},{"fixed":"b041733473f95119dd539542a43c280737a8e460"}],"database_specific":{"source":"AFFECTED_FIELD","extracted_events":[{"introduced":"0"},{"fixed":"0.22.0"}]}}],"versions":["v0.21.1","v0.21.0","v0.20.1","v0.20.0","v0.19.0","v0.18.1","v0.18.0","v0.17.0","v0.16.1","v0.16.0","v0.15.0","v0.14.3","v0.14.2","v0.14.1","v0.14.0","v0.13.1","v0.13.0","v0.12.0","v0.11.12","v0.11.11","v0.11.10","v0.11.9","v0.11.8","v0.11.7","v0.11.6","v0.11.5","v0.11.4","v0.11.3","v0.11.2","v0.11.1","v0.11.0","v0.10.6","v0.10.5","v0.10.4","v0.10.3","v0.10.2","v0.10.1","v0.10.0","v0.9.0","v0.8.4","v0.8.3","v0.8.2","v0.8.1","v0.8.0","v0.7.1","v0.7.0","v0.6.5","v0.6.4","v0.6.3","v0.6.2","v0.6.1","v0.6.0","v0.5.0","v0.4.0","v0.3.1","v0.3.0","v0.2.6","v0.2.5","v0.2.4","v0.2.3","v0.2.2","v0.2.1","v0.2.0","v0.1.16","v0.1.15","v0.1.14","v0.1.13","v0.1.12","v0.1.11","v0.1.10","v0.1.8","v0.1.7","v0.1.6","v0.1.5","v0.1.4"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77272.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"}]}