How severe is CVE-2026-77271?

CVE-2026-77271 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-77271 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-77271?

CVE-2026-77271 affects Mcp-atlassian Mcp Atlassian. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-77271?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-77271 published?

CVE-2026-77271 was published on 2026-09-22 and last updated on 2026-09-28.

CVE-2026-77271

CVE-2026-77271 is a high-severity vulnerability in Mcp-atlassian Mcp Atlassian with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v4: 8.3
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-22
Affected product: Mcp-atlassian Mcp Atlassian
Published: 2026-09-22
Last modified: 2026-09-28

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.

Frequently asked questions

What is CVE-2026-77271?: 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.
How severe is CVE-2026-77271?: CVE-2026-77271 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-77271 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-77271?: CVE-2026-77271 affects Mcp-atlassian Mcp Atlassian. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-77271?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-77271 published?: CVE-2026-77271 was published on 2026-09-22 and last updated on 2026-09-28.

References

Affected products (1)

cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:*

More vulnerabilities in Mcp-atlassian Mcp Atlassian

CVE-2026-77244 — Critical (CVSS 10.0): MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0,…
CVE-2026-77254 — Critical (CVSS 9.1): MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0,…
CVE-2026-27825 — Critical (CVSS 9.0): MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version…
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CVE-2026-77262 — High (CVSS 8.6): MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0,…
CVE-2026-77255 — High (CVSS 8.6): MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0,…

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