CVE-2026-77247 sooperset CVE debrief

Who should care

Defenders responsible for MCP Atlassian deployments, particularly those in remote or multi-user environments, should assess exposure and apply the patch to prevent potential file disclosure.

Why it matters

CVE-2026-77247 is a vulnerability in MCP Atlassian that allows permitted clients to disclose host files. Defenders should prioritize verifying exposure and applying the patch to prevent potential file disclosure.

• Verify exposure by checking the current version of MCP Atlassian.
• Apply patch to prevent potential file disclosure.
• Monitor for potential file disclosure attempts.
• Update incident response plans to address potential exploitation.

Technical summary

MCP Atlassian, a Model Context Protocol (MCP) server for Atlassian products, has a vulnerability that allows permitted clients to disclose host files without shell or direct filesystem access. The issue arises from the interpretation of caller-controlled path arguments on the MCP server, which opens files before sending them as attachments. This vulnerability is fixed in version 0.22.0. The vulnerability affects remote or multi-user deployments, and defenders should prioritize verifying exposure and applying the patch to prevent potential file disclosure.

Defensive priority

Defenders should prioritize verifying exposure and applying the patch to prevent potential file disclosure.

Recommended defensive actions

• Verify exposure by checking the current version of MCP Atlassian and identifying if it is prior to 0.22.0.
• Apply the patch by updating to version 0.22.0 or later.
• Monitor for potential file disclosure attempts.
• Review and update incident response plans to address potential exploitation.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.
• Review compensating controls for exposed systems while remediation is scheduled and verified.

Evidence notes

The vulnerability is described in the CVE record and NVD vulnerability detail page. The issue is fixed in version 0.22.0, as noted in the release notes and patch information. The CVE record was published on 2026-09-22T19:16:48.877Z and has not been modified since then. The vulnerability allows permitted clients to disclose host files without shell or direct filesystem access. Defenders should verify exposure by checking the current version of MCP Atlassian and identifying if it is prior to 0.22.0.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.