CVE-2026-27826: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira)

Q: How do I fix CVE-2026-27826?

mcp atlassian: upgrade to 0.17.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-27826 being exploited?

CVE-2026-27826 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-27826 affect?

CVE-2026-27826 affects mcp atlassian. Severity is high (CVSS 8.2). 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 out

Q: How urgent is CVE-2026-27826?

Priority 58/100. High severity; EPSS top 4%: very likely to be exploited; Public exploit reference

This week

HIGH 8.2UPGRADE

CVE-2026-27826 is a high-severity flaw (CVSS 8.2) affecting mcp atlassian. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

High severity
EPSS top 4%: very likely to be exploited
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.2 (High)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	13.0% (top 4%)
CISA exploited list	No
Weakness	CWE-918
Published	2026-03-10
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: sooperset

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-10 19:17 UTCPublished CVE record published
2026-06-17 10:27 UTCUpdated Record last modified

sooperset mcp atlassian UPGRADE

Affected: < 0.17.0

Fixed in: 0.17.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy mcp-atlassian || rpm -q mcp-atlassian || mcp-atlassian --version

2. UPGRADE to 0.17.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade mcp-atlassian

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade mcp-atlassian

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Python (pip) · mcp-atlassian · FIXED · 0.17.0 · vulnerable: < 0.17.0 · source

pip install --upgrade "mcp-atlassian>=0.17.0" pip show mcp-atlassian

Fedora 46 · python-hatchling · FIXED · 1.33.0-1.fc46 · FEDORA-2026-3ccbf17812 · source

sudo dnf upgrade --advisory=FEDORA-2026-3ccbf17812

Fedora ELN · pie · FIXED · 1.5.3-1.eln159 · FEDORA-2026-e009523caa · source

sudo dnf upgrade --advisory=FEDORA-2026-e009523caa

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Write-up: github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9
Nuclei scan template: mcp-atlassian < 0.17.0 - Server-Side Request Forgery

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-27826?

mcp atlassian: upgrade to 0.17.0. Exact commands for each OS are on this page.

Is CVE-2026-27826 being exploited?

CVE-2026-27826 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-27826 affect?

CVE-2026-27826 affects mcp atlassian. Severity is high (CVSS 8.2). 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 out

How urgent is CVE-2026-27826?

Priority 58/100. High severity; EPSS top 4%: very likely to be exploited; Public exploit reference

Software pages

Atlassian Confluence vulnerabilities · Atlassian Jira vulnerabilities

Related CVEs

CVE-2026-77265 MEDIUM 5.9 UPGRADE MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira)
CVE-2026-77267 MEDIUM 6.5 UPGRADE MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira)
CVE-2026-77249 MEDIUM 5.3 UPGRADE MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira)
CVE-2026-77257 MEDIUM 6.5 UPGRADE MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira)
CVE-2026-77262 HIGH 8.6 UPGRADE MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira)

References

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