CVE-2026-27826 Scanner

MCP Atlassian is widely used by organizations to integrate Atlassian products for enhanced productivity and resource management. This software serves as a middleware connecting various services within a network, frequently utilized by IT teams and project managers. Its primary goal is to streamline workflows and improve communication across different platforms, making it a valuable tool in enterprise environments. Due to this widespread use, ensuring its security is critical, as vulnerabilities can affect numerous connected systems. The software is primarily deployed in server environments accessible over internal networks and sometimes from external points. It integrates with various Atlassian products, providing comprehensive management and operational capabilities.

Server-Side Request Forgery (SSRF) allows malicious attackers to induce a server-side application to make HTTP requests to an arbitrary domain of the attacker's choosing. This vulnerability can be exploited by improper validation of custom headers, enabling attackers to manipulate the server's request methods. In this case, the vulnerability resides in the mcp-atlassian software, allowing unauthenticated attackers to exploit the flaw through HTTP endpoints. By doing so, attackers can perform unauthorized actions, potentially accessing sensitive internal resources or exposing the system to further attacks. The SSRF vulnerability in mcp-atlassian underlines the need for robust input validation and secured communication protocols.

The SSRF vulnerability in mcp-atlassian is exploited via improper validation in the HTTP middleware, specifically through custom HTTP headers. The vulnerable endpoint is accessed via HTTP requests that manipulate the 'X-Atlassian-Jira-Url' header to direct server requests to arbitrary URLs. This issue arises when the server does not adequately check or filter the URLs specified in these custom headers. As a result, attackers can force the server to interact with unintended endpoints, bypassing network restrictions or security measures. This weakness is primarily found in mcp-atlassian versions prior to 0.17.0.

When exploited, this SSRF vulnerability can lead to severe implications, such as unauthorized access to internal network resources, information disclosure, and potential data theft. Attackers might leverage the flaw to conduct further reconnaissance within the victim's infrastructure, identify potential weak points, or exfiltrate sensitive data. This could also facilitate other attacks, such as breaching databases, compromising additional systems, or conducting social engineering attacks with the acquired information. The broader impact of exploiting this vulnerability underscores the importance of implementing correct security patches and validating incoming requests properly.

REFERENCES

• https://pluto.security/blog/mcpwnfluence-cve-2026-27825-critical/
• https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-7r34-79r5-rcc9
• https://github.com/sooperset/mcp-atlassian/pull/986
• https://nvd.nist.gov/vuln/detail/CVE-2026-27826