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Advisory record · GHSA-w66g-j6c4-hcfc

MCP Atlassian: JIRA_PROJECTS_FILTER / CONFLUENCE_SPACES_FILTER allow forbidden-project content exfiltration (one LIVE-proven on Atlassian Cloud)

CVSS 8.3 HighEPSS 0.0027 · 18th percentile

Published by the GitHub Advisory Database at 22 Sept 2026, 20:34 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
mcp-atlassianPyPI<0.22.00.22.0
Identifiers
GHSA-w66g-j6c4-hcfc · CVE-2026-77251 · PYSEC-2026-4102
Weakness (CWE)
CWE-184 · CWE-693 · CWE-863 · CWE-1276
Tags
Published
22 Sept 2026
Updated
1 Oct 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

The mcp-atlassian PyPI package, versions before 0.22.0, does not fully enforce the JIRA_PROJECTS_FILTER and CONFLUENCE_SPACES_FILTER restrictions. An attacker who can send queries to the MCP server, such as a prompt-injected LLM agent, can read content from Jira or Confluence projects and spaces outside the operator's allowlist. Upgrade to mcp-atlassian 0.22.0 or later. The source gives few details on any workaround other than restricting untrusted MCP client input.

Written 1 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
8.3 High 4.0 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0027, the 18th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 14:09 UTC First seen by agentprime
  2. 31 Oct 2026, 14:09 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.