High File handling

CVE-2026-27825 — MCP Atlassian has an arbitrary file write leading to arbitrary code execution via unconstrained download_path in confluence_download_attachment

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, the `confluence_download_attachment` MCP tool accepts a `download_path` parameter that is written to without any directory boundary enforcement. An attacker who can call this tool and supply or access a Confluence attachment with malicious content can write arbitrary content to any path the server process has write access to. Because the attacker controls both the write destination and the written content (via an uploaded Confluence attachment), this constitutes for arbitrary code execution (for example, writing a valid cron entry to `/etc/cron.d/` achieves code execution within one scheduler cycle with no server restart required). Version 0.17.0 fixes the issue.

Published Mar 10, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 1.5% (30-day exploitation probability)+11
Technical severity (high)+6
CISA SSVC: exploitation "poc"+5

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

1.53%

ahead of 74% of scored CVEs · Oct 15, 2026

Affects

Mcp-atlassian

Mcp Atlassian

CVSS base

8.0

High · 3 source(s)

Prioritization reference: 9.1 provisional

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Proof of concept

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Documented patch — github.com (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Mcp-atlassian Mcp Atlassian, Sooperset Mcp Atlassian).
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Mcp-atlassian	Mcp Atlassian	< 0.17.0	Vulnerable	NIST National Vulnerability Database
Sooperset	Mcp Atlassian	version < 0.17.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Adjacent

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.1	CVSS 3.1	Critical	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP
9.0	CVSS 3.1	Critical	2.3	6.0	security-advisories@github.com via NIST National Vulnerability Database
8.0	CVSS 3.1	High	2.1	5.9	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: nvd@nist.gov)

Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 9.1 (GitHub_M via CVE Program (cve.org) e CISA ADP) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-22 · Path Traversal

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 1.53%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Monitor file creation in web directories and paths with traversal sequences (../).

file integrity (FIM)endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

2026
Affected products added · sooperset/mcp-atlassian
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
Fix documented
Oct 13, 2026 · NIST National Vulnerability Database
CVSS changed · 8.0
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Mar 10, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

2 on the record

github.com/sooperset/mcp-atlassian/security/advisories/GHSA-xjgw-4wvw-rgm4
Vendor Advisory, x_refsource_CONFIRM, NIST National Vulnerability Database
github.com/sooperset/mcp-atlassian/commit/52b9b0997681e87244b20d58034deae89c9163
Patch, x_refsource_MISC, NIST National Vulnerability Database

Elsewhere on this site

Mcp-atlassian
every CVE for this vendor

File handling
same class

CWE-22
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-77272 MCP Atlassian: Reflected XSS in OAuth Setup Callback Handler 23d
High CVE-2026-77259 MCP Atlassian: Arbitrary file read via confluence_upload_attachment allows exfiltration of server credentials 23d
Medium CVE-2026-77256 MCP Atlassian: OAuth refresh-token backup file is world-readable under default Unix umask 23d
Medium CVE-2026-77257 MCP Atlassian: HTTP upload tools accept arbitrary server-local file paths 23d
High CVE-2026-77262 MCP Atlassian: Path Traversal / Arbitrary File Read in confluence_upload_attachment MCP tool (incomplete fix of CVE-2026-27825) 23d
Medium CVE-2026-77269 MCP Atlassian: Path traversal in upload_attachment allows arbitrary file read (incomplete fix for CVE-2026-27825) 23d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-27825 is "MCP Atlassian has an arbitrary file write leading to arbitrary code execution via unconstrained download_path in confluence_download_attachment", rated High. It affects Mcp Atlassian (Mcp-atlassian); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.0 describes technical severity. EPSS 1.53% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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