CVE-2026-77268

Status: AnalyzedMedium (5.5)—

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the OAuth fallback token directory and JSON file are created without explicit owner-only modes. Local users or processes with access through the resulting group or world permission bits can read access and refresh tokens and reuse the associated Atlassian session. The advisory traces the vulnerable input and processing flow through ~/.mcp-atlassian, oauth-<client_id>.json, access_token, and refresh_token, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

CVSS

Version: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Base score: 5.5

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days: 0.12%
Percentile among all scored CVEs: 2
Score date: 10/6/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

🎯 ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

ExploitationT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Primary impactT1552.007 Container APIcredential access90 %
Secondary impactT1078.004 Cloud Accountsstealth · persistence · privilege escalation · initial access80 %

CWE-732 (permisos incorrectos en directorio local) permite a usuarios locales con permisos de grupo/mundo leer tokens OAuth almacenados en ~/.mcp-atlassian/oauth-*.json, reutilizando sesiones Atlassian (AV:L, PR:L).

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

🛡️ ATT&CK mitigations that cover these techniques

User Account Management Privileged Account Management Active Directory Configuration User Training Threat Intelligence Program Password Policies

Affected technologies (1)

Mcp-atlassian — MCP Atlassian

CWEs

CWE-732

References

Raw JSON (NVD)

Show

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