CVE-2026-77256

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Source
https://cve.org/CVERecord?id=CVE-2026-77256
Import Source
https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77256.json
JSON Data
https://api.osv.dev/v1/vulns/CVE-2026-77256
Aliases
  • GHSA-76pr-5669-3xf5
Published
2026-09-22T18:48:58Z
Modified
2026-09-24T03:45:58Z
Severity
  • 8.3 (High) CVSS_V4 - 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 CVSS Calculator
Summary
MCP Atlassian: OAuth refresh-token backup file is world-readable under default Unix umask
Details

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.

Database specific 
{
    "cna_assigner":  "GitHub_M",
    "cwe_ids":  [
        "CWE-732"
    ],
    "osv_generated_from":  "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77256.json"
}
References

Affected packages

Git / github.com/sooperset/mcp-atlassian

Affected ranges

Type
GIT
Repo
https://github.com/sooperset/mcp-atlassian
Events
Introduced
0 Unknown introduced commit / All previous commits are affected
Fixed
b041733473f95119dd539542a43c280737a8e460
Database specific
Show details 
{
    "extracted_events":  [
        {
            "introduced":  "0"
        },
        {
            "fixed":  "0.22.0"
        }
    ],
    "source":  [
        "AFFECTED_FIELD",
        "REFERENCES"
    ]
}

Affected versions

v0.*
v0.1.10
v0.1.11
v0.1.12
v0.1.13
v0.1.14
v0.1.15
v0.1.16
v0.1.4
v0.1.5
v0.1.6
v0.1.7
v0.1.8
v0.10.0
v0.10.1
v0.10.2
v0.10.3
v0.10.4
v0.10.5
v0.10.6
v0.11.0
v0.11.1
v0.11.10
v0.11.11
v0.11.12
v0.11.2
v0.11.3
v0.11.4
v0.11.5
v0.11.6
v0.11.7
v0.11.8
v0.11.9
v0.12.0
v0.13.0
v0.13.1
v0.14.0
v0.14.1
v0.14.2
v0.14.3
v0.15.0
v0.16.0
v0.16.1
v0.17.0
v0.18.0
v0.18.1
v0.19.0
v0.2.0
v0.2.1
v0.2.2
v0.2.3
v0.2.4
v0.2.5
v0.2.6
v0.20.0
v0.20.1
v0.21.0
v0.21.1
v0.3.0
v0.3.1
v0.4.0
v0.5.0
v0.6.0
v0.6.1
v0.6.2
v0.6.3
v0.6.4
v0.6.5
v0.7.0
v0.7.1
v0.8.0
v0.8.1
v0.8.2
v0.8.3
v0.8.4
v0.9.0

Database specific

source 
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-77256.json"