gcdRadar
archive/Patch now/AIR-2026-0161
closedclosed 22 Sep 2026Patch now2 Disclosed vulnerabilityAI

CVE-2026-77255: MCP Atlassian Arbitrary File Read and Exfiltration Vulnerability

MCP Atlassian

An insecure file handling vulnerability in MCP Atlassian allows callers to trick the server into reading arbitrary local files and attaching them to Jira issues. This acts as a confused deputy vector for data exfiltration.

disclosed CVENo confirmed exploitation, so this record is tracked as a disclosed vulnerability and not counted as an incident. It moves into the counts if CISA or the vendor confirms exploitation. Why

CVSS
8.6
EPSS
<0.01 · top 60% · 2026-11-13
EPSS scores by FIRST
fix status
Fix status unknown
first report
22 Sep 2026
last update
22 Sep 2026
CVE ids
CVE-2026-77255other records

Timeline · 1

  1. 22 Sep 2026CVE-2026-77255: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira).

Sources · 1

Advisories and databases

  1. 2026-09-22
    CVE-2026-77255: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira).
    NVD · nvd.nist.gov/vuln/detail/CVE-2026-77255

Titles and links belong to their publishers. The summary above is written by gcdRadar in its own words; data is CC BY-SA 4.0.

Classification

lane
Patch now
AI role
Attack on AI
categories
Infrastructure vulnerabilityAgent hijack
severity
2 · Disclosed vulnerability
fix status
Fix status unknown
targets
Framework / tooling
owasp llm top 10
LLM03:2025 Supply ChainLLM06:2025 Excessive Agency
mitre atlas
AML.T0053 AI Agent Tool Invocation
tags
mcpconfused-deputyarbitrary-file-read
dates
happened 22 Sep 2026 · first reported 22 Sep 2026
origin
NVD
Vulnerability record from NVD / the GitHub Advisory Database. This product uses the NVD API but is not endorsed or certified by the NVD.
record
confidence 0.95 · created 2026-10-18 06:33Z · updated 2026-10-18 06:33Z

Lane, AI role, categories and severity come from the classifier; the OWASP and ATLAS rows are derived from the categories. How these are assigned

Copy a brief

This record as a short Markdown brief, for a ticket, a chat or a coding agent.

the brief as text
# CVE-2026-77255: MCP Atlassian Arbitrary File Read and Exfiltration Vulnerability

https://gcdradar.vercel.app/incidents/cve-2026-77255-mcp-atlassian-arbitrary-file-read-and-exfiltr · AIR-2026-0161 · closed 2026-09-22

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-09-22
- AI role: Attack on AI
- Products: MCP Atlassian
- CVE ids: CVE-2026-77255
- CVSS: 8.6

## Summary

An insecure file handling vulnerability in MCP Atlassian allows callers to trick the server into reading arbitrary local files and attaching them to Jira issues. This acts as a confused deputy vector for data exfiltration.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2026-09-22: CVE-2026-77255: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). (https://nvd.nist.gov/vuln/detail/CVE-2026-77255)

## Sources

- 2026-09-22 NVD: CVE-2026-77255: MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). https://nvd.nist.gov/vuln/detail/CVE-2026-77255

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.

Related

  1. closed8.8
    MCP servers & tools CVE-2026-77243: MCP Atlassian fails to recheck tool restrictions on dispatch

    Patch now · Disclosed · since 22 Sep 2026 · CVE-2026-77243

    AI
  2. closed7.7
    MCP servers & tools CVE-2026-73498: Path traversal flaw in MCP Atlassian server allows arbitrary file read

    Patch now · Disclosed · since 12 Aug 2026 · CVE-2026-73498

    AI
  3. closed
    OpenCode OpenCode Flaw Allows Malicious MCP Servers to Execute Code

    Patch now · Disclosed · since Sep 2026 (approx.)

    AI
  4. closed8.3
    Langflow CVE-2026-107366: IBM Langflow OSS lacks ownership verification on message endpoints enabling session hijacking

    Patch now · Disclosed · since 20 Oct 2026 · CVE-2026-107366

    AI
  5. closed9.6
    MCP servers & tools CVE-2026-61559: Dynamic API URL redirection flaw in mcp-gitlab

    Patch now · Disclosed · since 15 Sep 2026 · CVE-2026-61559

    AI
  6. closed9.8
    MCP servers & tools CVE-2026-61560: Authentication bypass and arbitrary file read in mcp-gitlab

    Patch now · Disclosed · since 15 Sep 2026 · CVE-2026-61560

    AI