High 8.3Published Sep 22, 2026

CVE-2026-77256MCP Atlassian: OAuth refresh-token backup file is world-readable under default Unix umask

Updated under an hour ago (2026-10-19 09:00 UTC)

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It affects sooperset mcp-atlassian and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for sooperset mcp-atlassian

Exploited in the last 30 days

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, the plaintext OAuth fallback file containing refresh and access tokens is written with permissions inherited from the process umask. Under common or permissive configurations, other local users can read the backup and retain Atlassian access through the refresh token. The advisory traces the vulnerable input and processing flow through OAuthConfig._save_tokens_to_file, refresh_token, access_token, and umask, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

CVSS: 8.3 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-732
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Analyzed
Record last updated: Sep 22, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

sooperset mcp-atlassian sooperset:mcp_atlassian (from the name)	before 0.22.0	CNA record
mcp-atlassian mcp_atlassian mcp-atlassian:mcp_atlassian	before 0.22.0	NVD

References

https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-76pr-5669-3xf5x-refsource-confirm, mitigation, vendor-advisory
https://github.com/sooperset/mcp-atlassian/pull/1448x-refsource-misc, issue-tracking, patch
https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460x-refsource-misc, patch
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0x-refsource-misc, release-notes

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.