What is CVE-2026-77242?

CVE-2026-77242 is a high-severity vulnerability in Sooperset Mcp-Atlassian, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.5/10. Published 2026-09-22.

How severe is CVE-2026-77242?

High severity. CVSS v3 base score is 7.5 out of 10.

SSRF in Sooperset Mcp-Atlassian

CVE-2026-77242

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.

Vulnerability class: TOCTOU (Time-of-Check to Time-of-Use)

Published 2026-09-22 · last modified 2026-09-22.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:L/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Sooperset Mcp-Atlassian — versions < 0.22.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-77242?: CVE-2026-77242 is a high-severity vulnerability in Sooperset Mcp-Atlassian, classified under Time-of-check Time-of-use (TOCTOU) Race Condition. CVSS score: 7.5/10. Published 2026-09-22.
How severe is CVE-2026-77242?: High severity. CVSS v3 base score is 7.5 out of 10.