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NVD / CVE Program· CNA GitHub_M

CVE-2026-77268: MCP Atlassian: Insecure File Permissions on OAuth Token Storage

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.15% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: sooperset mcp-atlassian 0.22.0.

Low priority for now. Upgrade to sooperset mcp-atlassian 0.22.0 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Sep 22, 2026
Updated
Sep 29, 2026
EPSS
0.1% · 4th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitHub_M
5.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mcp-atlassianmcp atlassian

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mcp-atlassian mcp atlassianbefore 0.22.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • sooperset mcp-atlassian

    • < 0.22.0affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
PyPImcp-atlassianbefore 0.22.00.22.0

Same product

mcp-atlassian: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-77244[mcp-atlassian] Authentication bypass in HTTP transport: AtlassianOpaqueTokenVerifier accepts any non-empty token
    40Plan
  • CVE-2026-77254MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials
    36Monitor
  • CVE-2026-27825MCP Atlassian has an arbitrary file write leading to arbitrary code execution via unconstrained download_path in confluence_download_attachment
    36Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-77259Sep 22, 2026 · MCP Atlassian: Arbitrary file read via confluence_upload_attachment allows exfiltration of server credentials
    30Monitor
  • ← EarlierCVE-2026-77262Sep 22, 2026 · MCP Atlassian: Path Traversal / Arbitrary File Read in confluence_upload_attachment MCP tool (incomplete fix of CVE-2026-27825)
    34Monitor
  • Later →CVE-2026-77269Sep 22, 2026 · MCP Atlassian: Path traversal in upload_attachment allows arbitrary file read (incomplete fix for CVE-2026-27825)
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
sooperset mcp-atlassian0.22.0 · descriptionVendor (CNA)
PyPI:mcp-atlassian0.22.0Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-772560 days apartMCP Atlassian: OAuth refresh-token backup file is world-readable under default Unix umask
    33Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
none
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-732 · Incorrect Permission Assignment for Critical Resource

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records