CVE-2026-77274 MCP Atlassian: SSRF Protection Bypass
An attacker can bypass SSRF protections in MCP Atlassian to access internal network resources via crafted URLs.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-77274?
CVE-2026-77274 is a high-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 22 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, validate_url_for_ssrf has a backslash authority confusion because it interprets the authority differently from the Requests connection layer in the header-based Jira and Confluence URL authentication flow. A crafted URL can validate as an external hostname while the HTTP client connects to an internal host, permitting server-side requests to protected network resources. This issue is fixed in version 0.22.0.
Weakness: CWE-918
Which versions are affected by CVE-2026-77274?
3 open source packages ship an affected version, including mcp-atlassian. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mcp-atlassian PyPI | All versions | 0.22.0 |
mcp-atlassian PyPI | All versions | 0.22.0 |
mcp-atlassian PyPI | All versions | 0.22.0 |
Products include Mcp-Atlassian Mcp Atlassian.
How do I fix CVE-2026-77274?
Upgrade mcp-atlassian to 0.22.0 or later.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-77274 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77274 exists.
Other vulnerabilities in sooperset mcp-atlassian
- CVE-2026-77244 [mcp-atlassian] Authentication bypass in HTTP transport: AtlassianOpaqueTokenVerifier accepts any non-empty token
- CVE-2026-77254 MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials
- CVE-2026-27825 MCP Atlassian has an arbitrary file write leading to arbitrary code execution via unconstrained download_path in confluence_download_attachment
- CVE-2026-77243 MCP Atlassian: ENABLED_TOOLS / Toolset authorization bypass
- CVE-2026-77248 MCP Atlassian: Unauthenticated arbitrary local file read via upload_attachment file_path, chained with missing auth on streamable-http transport
Sources
Also known as GHSA-hgcf-4mq8-5266, PYSEC-2026-4096.