CVE-2026-77258
MCP Atlassian: Arbitrary file read/exfiltration via upload_attachment missing validate_safe_path()
Description
MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, upload_attachment in src/mcp_atlassian/confluence/attachments.py accepts a caller-controlled file_path and opens the selected server-local file without restricting it to the workspace. A permitted Confluence MCP caller can upload the file as an attachment and disclose data readable by the server process. This issue is fixed in version 0.22.0.
INFO
Published Date :
Sept. 22, 2026, 6:17 p.m.
Last Modified :
Sept. 29, 2026, 2:01 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-77258
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | [email protected] |
Solution
- Update MCP Atlassian to version 0.22.0 or later.
- Restrict file access to the workspace.
- Validate all file path inputs.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-77258.
| URL | Resource |
|---|---|
| https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 | Patch |
| https://github.com/sooperset/mcp-atlassian/pull/1448 | Issue Tracking Patch |
| https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 | Release Notes |
| https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-93xw-j965-9mx3 | Exploit Vendor Advisory |
| https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-93xw-j965-9mx3 | Exploit Vendor Advisory |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-77258 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-77258
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-77258 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-77258 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Sep. 29, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:mcp-atlassian:mcp_atlassian:*:*:*:*:*:*:*:* versions up to (excluding) 0.22.0 Added Reference Type GitHub, Inc.: https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/sooperset/mcp-atlassian/pull/1448 Types: Issue Tracking, Patch Added Reference Type GitHub, Inc.: https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 Types: Release Notes Added Reference Type CISA-ADP: https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-93xw-j965-9mx3 Types: Exploit, Vendor Advisory Added Reference Type GitHub, Inc.: https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-93xw-j965-9mx3 Types: Exploit, Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Sep. 26, 2026
Action Type Old Value New Value Added Reference https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-93xw-j965-9mx3 Added SSVC {'id': 'CVE-2026-77258', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-09-25T23:48:48.170129Z'} -
New CVE Received by [email protected]
Sep. 22, 2026
Action Type Old Value New Value Added Description MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, upload_attachment in src/mcp_atlassian/confluence/attachments.py accepts a caller-controlled file_path and opens the selected server-local file without restricting it to the workspace. A permitted Confluence MCP caller can upload the file as an attachment and disclose data readable by the server process. This issue is fixed in version 0.22.0. Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N Added CWE CWE-22 Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/77xxx/CVE-2026-77258.json">CVE-2026-77258</a> Added Reference https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460 Added Reference https://github.com/sooperset/mcp-atlassian/pull/1448 Added Reference https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0 Added Reference https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-93xw-j965-9mx3