CVE-2026-77246 MCP Atlassian - Authorization Bypass

MCP Atlassian < 0.22.0 contains an authorization bypass caused by accepting requests without identity and allowing attacker-controlled service headers, letting attackers upload server-local files to attachment endpoints, exploit requires READ_ONLY_MODE=false.

CVSS base score 7.4 /10
High
CISA KEV
Not listed
Public exploit
Proof of concept available
Authentication
Not required
EPSS
0.43% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Authorization Bypass
Impact
Data Tampering, File System Write
CVSS vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
Published
22 September 2026
Updated
15 October 2026
Weakness
CWE-22

Vendor fix

Update to version 0.22.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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