CVE-2026-77272: sooperset mcp-atlassian · Cross-site Scripting
Affects sooperset mcp-atlassianSource CVE Database V5
Not known to be exploited · CVSS 5.4 Medium : upgrade to 0.22.0 when convenient.
Data as of 5 Nov 2026, 23:24 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 18% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.22.0
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 22 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.
What to do
Upgrade mcp-atlassian and sooperset/mcp-atlassian to 0.22.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| soopersetmcp-atlassian | Affected
| Fixed in
|
GitHubsooperset/mcp-atlassianpkg:github/sooperset/mcp-atlassianOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Upgrade sooperset mcp-atlassian to version 0.22.0 or later, where this XSS vulnerability is fixed. No other mitigation is indicated or required by the vendor advisory.
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.
References
- github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g2r2-3j32-j27x (opens in a new tab)
- github.com/sooperset/mcp-atlassian/pull/1448 (opens in a new tab)
- github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 (opens in a new tab)
- github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 (opens in a new tab)