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CVE-2026-27825 is an improper pathname restriction vulnerability in MCP Atlassian versions earlier than 0.17.0. The Confluence attachment-download MCP tool accepts an attacker-controlled destination path and writes downloaded attachment content without enforcing that the resolved path remains within an approved directory. A caller able to invoke the tool and access or supply an attacker-controlled Confluence attachment can control both the file content and its destination, allowing arbitrary file writes with the privileges of the MCP Atlassian server process. This may be escalated to code execution by overwriting or creating files consumed by an execution mechanism, such as scheduler configuration or user startup configuration.
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No valid public exploits. Mallory filtered out 2 candidates as fakes, detection scripts, or README-only repos.
All candidate exploits were filtered out by Mallory's validation.
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Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
29 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A previously reported unauthenticated remote-code-execution and server-side request forgery vulnerability in Atlassian MCP, mentioned solely as a related comparison; it is not the vulnerability disclosed by this advisory.
An arbitrary-file-write vulnerability in mcp-atlassian's attachment download path. Its v0.17.0 remediation introduced validate_safe_path() for write operations but incompletely addressed the analogous upload-side arbitrary-file-read flaw.
A prior mcp-atlassian path-validation vulnerability for which download operations received validate_safe_path() protection in version 0.17.0; the fix did not cover the vulnerable upload operations described in this advisory.
An earlier MCP Atlassian download vulnerability referenced as the source of a path-restriction control that was not applied to confluence_upload_attachment. No further technical details are provided.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.