{"cve":"CVE-2026-77272","nvd":{"published":"2026-09-22T19:16:51.177","modified":"2026-09-28T13:10:43.460","status":"Analyzed","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N","score":6.1},"cwes":["CWE-79"],"references":["https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460","https://github.com/sooperset/mcp-atlassian/pull/1448","https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0","https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g2r2-3j32-j27x"],"products":["mcp-atlassian:mcp_atlassian"],"source":"nvd","synced_at":"2026-10-19T22:56:02.509636177+00:00"},"epss":{"cve":"CVE-2026-77272","score":0.00262,"percentile":0.18061,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-g2r2-3j32-j27x","url":"https://osv.dev/vulnerability/GHSA-g2r2-3j32-j27x","summary":"MCP Atlassian: Reflected XSS in OAuth Setup Callback Handler","modified":"2026-10-01T17:56:06.097977063Z","packages":[{"ecosystem":"PyPI","name":"mcp-atlassian","purl":"pkg:pypi/mcp-atlassian","ranges":["<0.22.0"],"fixed":["0.22.0"]}]},{"id":"PYSEC-2026-4093","url":"https://osv.dev/vulnerability/PYSEC-2026-4093","summary":"MCP Atlassian: Reflected XSS in OAuth Setup Callback Handler","modified":"2026-10-01T17:45:09.287304448Z","packages":[{"ecosystem":"PyPI","name":"mcp-atlassian","purl":"pkg:pypi/mcp-atlassian","ranges":["<0.22.0"],"fixed":["0.22.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}