MCP Vulnerability in Atlassian Products Allows Unrestricted File Writes
CVE-2026-77271

8.3HIGH

Key Information:

Vendor

Sooperset

Status
Mcp-atlassian
Vendor
CVE Published:
22 September 2026

What is CVE-2026-77271?

The MCP Atlassian server enables attackers to manipulate the system by exploiting an issue in path validation. With default settings, the validate_safe_path function uses the current working directory, which can lead to unauthorized file writes in Confluence and Jira. When base_dir is omitted in attachment calls, an attacker could potentially overwrite Python modules, facilitating code execution upon later imports. This vulnerability has been addressed in version 0.22.0, emphasizing the need for users to upgrade to mitigate risks.

Affected Version(s)

mcp-atlassian < 0.22.0

References

https://github.com/sooperset/mcp-atlassian/security/advis...
x_refsource_CONFIRM
https://github.com/sooperset/mcp-atlassian/pull/1448
x_refsource_MISC
https://github.com/sooperset/mcp-atlassian/commit/b041733...
x_refsource_MISC

CVSS V4

Score:
8.3
Severity:
HIGH
Confidentiality:
High
Integrity:
None
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.