Reference page — cumulative record through Saturday, October 3, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-77250

CVE-2026-77250MEDIUM

sooperset mcp-atlassian — MCP Atlassian: OAuth fallback token storage writes plaintext access and refresh tokens with group-readable permissions

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   L   L   L   N  U  H  L  N    6.1   .0011    1.1     —

AFFECTED
  Product        Versions    Fixed
  mcp-atlassian  < 0.22.0 –  —

TIMELINE
  Aug 20  Reserved by GitHub_M
  Sep 22  Published (CNA: GitHub_M)
  Sep 29  EXPLOIT PUBLISHED — CVE-2026-77250 (sooperset mcp-atlassian). Public exploit reference added.

CWE-312 · CNA: GitHub_M · CVSS v3.1 · 4 references · NVD status: Analyzed

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, OAuthConfig writes a plaintext fallback file containing access and refresh tokens under the user's .mcp-atlassian directory using process-default permissions. On systems with a permissive umask, same-group or other local users and processes can read the persisted tokens and reuse the associated Atlassian access. The advisory traces the vulnerable input and processing flow through OAuthConfig._save_tokens, ~/.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.

Lifecycle

Complete event history — 3 events, chronological
Date	Event	Detail
August 20, 2026	Reserved	Reserved by GitHub_M
September 22, 2026	Published	Published (CNA: GitHub_M)
September 29, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-77250 (sooperset mcp-atlassian). Public exploit reference added.

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
sooperset	mcp-atlassian	—	< 0.22.0	—

Weaknesses

CWE-312

References (4)

https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 [Patch]
https://github.com/sooperset/mcp-atlassian/pull/1448 [Issue Tracking, Patch]
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 [Release Notes]
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-g5xv-mhgm-v5f6 [Exploit, Vendor Advisory]

Authoritative record: CVE-2026-77250 at cve.org

Vendors: sooperset

Weaknesses: CWE-312

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-77250 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Saturday, October 3, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.