CVE-2026-77255: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira)

Q: How do I fix CVE-2026-77255?

mcp atlassian: upgrade to 0.22.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-77255 being exploited?

CVE-2026-77255 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-2026-77255 affect?

CVE-2026-77255 affects mcp atlassian. Severity is high (CVSS 8.6). MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the Jira update_issue attachments argument is converted into local paths and routed to the attachment upload implementatio

Q: How urgent is CVE-2026-77255?

Priority 50/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 8.6REMOTEUPGRADE

CVE-2026-77255 is a high-severity flaw (CVSS 8.6) 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 0.22.0, the Jira update_issue attachments argument is converted into local paths and routed to the attachment upload implementation without workspace validation. A caller can make the MCP server read arbitrary local files and attach them to a Jira issue, using the server as a confused deputy to exfiltrate the contents. The advisory traces

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 60%)
CISA exploited list	No
Weakness	CWE-22, CWE-441
Published	2026-09-22
Last modified	2026-09-29

Publisher (CNA): GitHub, Inc. · Vendor: mcp-atlassian

Last updated 2026-09-29 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-22 19:16 UTCPublished CVE record published
2026-09-29 13:41 UTCUpdated Record last modified

mcp-atlassian mcp atlassian UPGRADE

Affected: < 0.22.0

Fixed in: 0.22.0

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 0.22.0 (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.

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-2026-77255?

mcp atlassian: upgrade to 0.22.0. Exact commands for each OS are on this page.

Is CVE-2026-77255 being exploited?

CVE-2026-77255 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-2026-77255 affect?

CVE-2026-77255 affects mcp atlassian. Severity is high (CVSS 8.6). MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the Jira update_issue attachments argument is converted into local paths and routed to the attachment upload implementatio

How urgent is CVE-2026-77255?

Priority 50/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

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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