CVE-2026-77271

MCP Atlassian: Incomplete path traversal fix allows intra-CWD module overwrite and RCE (bypass of CVE-2026-27825)

HIGH
8.8
CVSS Score
Published: September 22, 2026 at 06:00 PM UTC
Updated: September 28, 2026 at 01:45 PM UTC
2 products affected across 2 vendorsMcp AtlassianAtlassian Mcp Atlassian

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Severity
HIGH8.8
Exploit prediction
EPSS 0.6%
SSVC
PoC

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, validate_safe_path defaults its base directory to os.getcwd(), and affected Confluence attachment call sites omit base_dir, allowing attacker-selected writes within the working directory. This Python module overwrite can provide code execution when the application later imports the modified module, bypassing the remediation tracked as CVE-2026-27825. This issue is fixed in version 0.22.0.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.22.0
Affected range stops below 0.22.0, so it looks safe — our inference, not a vendor statement
v < 0.22.0
Affected range stops below 0.22.0, so it looks safe — our inference, not a vendor statement

References (4)

x_refsource_CONFIRMExploitVendor Advisory
Source: cverecord
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-6vmq-24h2-pj7j
x_refsource_MISCIssue TrackingPatch
Source: cverecord
https://github.com/sooperset/mcp-atlassian/pull/1448
x_refsource_MISCRelease Notes
Source: cverecord
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0

SSVC — Action Prioritization

SSVCPoCNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-22CWE-94

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