How severe is CVE-2026-77261?

CVE-2026-77261 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2026-77261 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-77261?

CVE-2026-77261 affects Mcp-atlassian Mcp Atlassian. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-77261?

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-2026-77261 published?

CVE-2026-77261 was published on 2026-09-22 and last updated on 2026-09-25.

CVE-2026-77261

CVE-2026-77261 is a high-severity vulnerability in Mcp-atlassian Mcp Atlassian with a CVSS 3.x base score of 7.1. 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-918.

Key facts

Severity: High (CVSS 3.x base score 7.1)
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-918
Affected product: Mcp-atlassian Mcp Atlassian
Published: 2026-09-22
Last modified: 2026-09-25

Description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, _make_ssrf_safe_hook is omitted from JiraFetcher and ConfluenceFetcher sessions created through the basic-auth and oauth_pat branches. If an attacker-controlled or compromised configured Atlassian instance returns a redirect to an internal address, those sessions can follow the redirect without revalidating its destination. This issue is fixed in version 0.22.0.

Frequently asked questions

What is CVE-2026-77261?: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, _make_ssrf_safe_hook is omitted from JiraFetcher and ConfluenceFetcher sessions created through the basic-auth and oauth_pat branches. If an attacker-controlled or compromised configured Atlassian instance returns a redirect to an internal address, those sessions can follow the redirect without revalidating its destination. This issue is fixed in version 0.22.0.
How severe is CVE-2026-77261?: CVE-2026-77261 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2026-77261 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-77261?: CVE-2026-77261 affects Mcp-atlassian Mcp Atlassian. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-77261?: 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-2026-77261 published?: CVE-2026-77261 was published on 2026-09-22 and last updated on 2026-09-25.

References

Affected products (1)

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

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