CVE-2026-77261

MCP Atlassian: SSRF redirect protection missing for basic-auth and OAuth authentication branches

HIGH
8.5
CVSS Score
Published: September 22, 2026 at 06:06 PM UTC
Updated: September 25, 2026 at 05:47 PM UTC
2 products affected across 2 vendorsMcp AtlassianAtlassian Mcp Atlassian

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Severity
HIGH8.5
Exploit prediction
EPSS 0.4%
SSVC
No known exploit

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.

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)

SSVC — Action Prioritization

SSVCNo known exploitNot 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
CHANGED
Confidentiality
HIGH
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-918

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