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CVE-2026-77271

Mcp-atlassian Mcp Atlassian code injection

8.8 HIGHPublic exploitEPSS 0.53%
  1. Published22 Sept 2026

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, validate_safe_path defaults its base directory to os.getcwd(), and affected Confluence attachment call sites omit base_dir, allowing attacker-selected writes within the working directory. This Python module overwrite can provide code execution when the application later imports the modified module, bypassing the remediation tracked as CVE-2026-27825. This issue is fixed in version 0.22.0.

CVSS 3.1 breakdown

Attack vectorNetwork
Attack complexityLow
Privileges requiredLow
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

Mcp-atlassian Mcp Atlassian< 0.22.0

Remediation

Fixed in
Mcp-atlassian Mcp Atlassian≥ 0.22.0

References

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Frequently asked

Is CVE-2026-77271 being actively exploited?

CVE-2026-77271 is not in the CISA KEV catalog. A public exploit reference exists, so treat it as exploitable. Its EPSS exploit probability is 0.53%.

How severe is CVE-2026-77271?

CVE-2026-77271 has a CVSS 3.1 base score of 8.8, rated high. EPSS estimates a 0.53% probability of exploitation.

Which products are affected by CVE-2026-77271?

Affected products include Mcp-atlassian Mcp Atlassian.

How do I fix CVE-2026-77271?

Upgrade affected software to a fixed version, for example Mcp-atlassian Mcp Atlassian 0.22.0 or later, then confirm no affected versions remain in your inventory.

How Secuno handles this

Secuno correlates vulnerabilities like CVE-2026-77271 against the real software inventory on every managed device, every day. Rather than a static severity, each match is scored in context: exploit availability, EPSS, the asset's exposure, and business criticality decide where it lands in the queue. If an affected version is present anywhere across your portfolio, it surfaces automatically with a prioritised remediation path.

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Data from the NVD, CISA KEV catalog and FIRST EPSS. CVSS 3.1 base score shown where available.