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Fencer Intel
high 8.2

CVE-2026-27826 in the critical feed json

MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers

published 7mo ago modified 3mo ago also EUVD-2026-10788 , GHSA-7r34-79r5-rcc9 , PYSEC-2026-2621

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
13.9%
EPSS 13.9% chance of exploitation in 30 days, percentile 96%
public exploits
0
none known, plus a Nuclei check

Summary

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, an unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169[.]254[.]169[.]254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. Version 0.17.0 fixes the issue.

Patch / fix

  • pypi mcp-atlassian 0.17.0
  • mcp-atlassian mcp_atlassian 0.17.0
  • sooperset mcp_atlassian 0.17.0

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
7mo ago

Exploit prediction

13.85% chance of exploitation in the next 30 days, higher than 96% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • Nuclei template mcp-atlassian < 0.17.0 - Server-Side Request Forgery nuclei detection template
  • github.com https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.2 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
GitHub 3.1 8.2 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
NVD 3.1 8.2 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N
OSV 3.1 8.2 CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N

Affected packages

ecosystem package affected fixed in
pypi mcp-atlassian
<0.17.0
0.17.0

Affected products

  • sooperset mcp-atlassian

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.