Vulnerability · Published Sep 22, 2026 · Assigned by GitHub_M

CVE-2026-77267mcp-atlassian has an incomplete SSRF remediation

High 8.3

In plain English

A high-severity server-side request forgery in mcp-atlassian from sooperset. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.3High

Exploit odds (30 days)0.3%top 74.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url headers are processed by _process_authentication_headers and used to construct Atlassian fetchers without calling validate_url_for_ssrf. A caller who can set these headers can supply an internal or metadata-service URL and cause the server to send requests to that destination, bypassing the incomplete CVE-2026-27826 remediation. This issue is fixed in version 0.22.0.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
PyPI	mcp-atlassian	0.22.0	GHSA-5wf4-jqxh-8gm3
PyPI	mcp-atlassian	0.22.0	PYSEC-2026-4084

Affected products (as reported)

Vendor	Product	Versions
sooperset	mcp-atlassian	< 0.22.0

Weakness: CWE-918 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

References

https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-5wf4-jqxh-8gm3 x_refsource_CONFIRM
https://github.com/sooperset/mcp-atlassian/pull/1448 x_refsource_MISC
https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 x_refsource_MISC
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 x_refsource_MISC