CVE-2026-77242: CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition in sooperset mcp-atlassian
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, validate_url_for_ssrf checks a hostname's resolved addresses, but Requests and urllib3 resolve the hostname again when connecting. A caller can use a short-lived DNS answer that is public during validation and private during connection, preserving unauthenticated access to internal or metadata endpoints despite the earlier CVE-2026-27826 remediation. The advisory traces the vulnerable input and processing flow through validate_url_for_ssrf, _check_dns_resolution, socket.getaddrinfo, and _make_ssrf_safe_hook, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
AI Analysis
Technical Summary
The vulnerability in sooperset mcp-atlassian involves a time-of-check to time-of-use (TOCTOU) race condition in the validate_url_for_ssrf function. The function checks a hostname's resolved addresses to prevent SSRF attacks, but the Requests and urllib3 libraries perform a separate hostname resolution when establishing the connection. An attacker can exploit this discrepancy by providing a short-lived DNS response that resolves to a public IP during validation but changes to a private or internal IP during connection, thereby bypassing SSRF protections. The affected code paths include validate_url_for_ssrf, _check_dns_resolution, socket.getaddrinfo, and _make_ssrf_safe_hook. The vulnerability is fixed in version 0.22.0.
Potential Impact
Successful exploitation allows unauthenticated attackers to bypass SSRF protections and access internal or metadata endpoints, potentially leading to disclosure of sensitive information. The CVSS score of 7.5 (high) reflects the network attack vector, high confidentiality impact, low integrity impact, and no availability impact.
Mitigation Recommendations
Upgrade sooperset mcp-atlassian to version 0.22.0 or later, where this TOCTOU race condition vulnerability is fixed. No other mitigation is indicated by the vendor advisory.
CVE-2026-77242: CWE-367: Time-of-check Time-of-use (TOCTOU) Race Condition in sooperset mcp-atlassian
Description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, validate_url_for_ssrf checks a hostname's resolved addresses, but Requests and urllib3 resolve the hostname again when connecting. A caller can use a short-lived DNS answer that is public during validation and private during connection, preserving unauthenticated access to internal or metadata endpoints despite the earlier CVE-2026-27826 remediation. The advisory traces the vulnerable input and processing flow through validate_url_for_ssrf, _check_dns_resolution, socket.getaddrinfo, and _make_ssrf_safe_hook, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
CVSS v3.1
Score 7.5high
Affected software
sooperset
mcp-atlassian
pkg:github/sooperset/mcp-atlassianRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in sooperset mcp-atlassian involves a time-of-check to time-of-use (TOCTOU) race condition in the validate_url_for_ssrf function. The function checks a hostname's resolved addresses to prevent SSRF attacks, but the Requests and urllib3 libraries perform a separate hostname resolution when establishing the connection. An attacker can exploit this discrepancy by providing a short-lived DNS response that resolves to a public IP during validation but changes to a private or internal IP during connection, thereby bypassing SSRF protections. The affected code paths include validate_url_for_ssrf, _check_dns_resolution, socket.getaddrinfo, and _make_ssrf_safe_hook. The vulnerability is fixed in version 0.22.0.
Potential Impact
Successful exploitation allows unauthenticated attackers to bypass SSRF protections and access internal or metadata endpoints, potentially leading to disclosure of sensitive information. The CVSS score of 7.5 (high) reflects the network attack vector, high confidentiality impact, low integrity impact, and no availability impact.
Mitigation Recommendations
Upgrade sooperset mcp-atlassian to version 0.22.0 or later, where this TOCTOU race condition vulnerability is fixed. No other mitigation is indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-20T19:02:23.415Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ab2c670f7a7c541068f922b
Added to database: 09/22/2026, 18:18:24 UTC
Last enriched: 09/22/2026, 18:32:54 UTC
Last updated: 09/22/2026, 19:33:28 UTC
Views: 7
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