# CVE-2026-27826: MCP Atlassian has SSRF via unvalidated X-Atlassian-Jira-Url / X-Atlassian-Confluence-Url headers

> Unauthenticated attackers can force the MCP Atlassian server to make arbitrary outbound requests, enabling internal network reconnaissance and potential credential theft.

- **Severity:** High 8.2 (`CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Mar 2026
- **Updated:** 10 Mar 2026
- **Also known as:** GHSA-7r34-79r5-rcc9, PYSEC-2026-2621

## What is CVE-2026-27826?

CVE-2026-27826 is a high-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 10 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to version 0.17.0, an unauthenticated attacker who can reach the mcp-atlassian HTTP endpoint can force the server process to make outbound HTTP requests to an arbitrary attacker-controlled URL by supplying two custom HTTP headers without an `Authorization` header. No authentication is required. The vulnerability exists in the HTTP middleware and dependency injection layer — not in any MCP tool handler - making it invisible to tool-level code analysis. In cloud deployments, this could enable theft of IAM role credentials via the instance metadata endpoint (`169[.]254[.]169[.]254`). In any HTTP deployment it enables internal network reconnaissance and injection of attacker-controlled content into LLM tool results. Version 0.17.0 fixes the issue.

Weakness: CWE-918 (Server-Side Request Forgery)

## Which versions are affected by CVE-2026-27826?

3 open source packages ship an affected version, including mcp-atlassian. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mcp-atlassian` | PyPI | All versions | 0.17.0 |
| `mcp-atlassian` | PyPI | All versions | 0.17.0 |
| `mcp-atlassian` | PyPI | All versions | 0.17.0 |

Products: Sooperset Mcp Atlassian.

## How do I fix CVE-2026-27826?

Upgrade mcp-atlassian to 0.17.0 or later.

## Is CVE-2026-27826 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27826 exists.

Public exploit code:

- mcp-atlassian < 0.17.0 - Server-Side Request Forgery (nuclei): http/cves/2026/CVE-2026-27826.yaml

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-27826 and fix it if it is affected.

What it is: CVE-2026-27826 is a high-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 10 Mar 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-27826 exists.

Affected packages and fixed versions:
- mcp-atlassian (PyPI): affected all versions; fixed in 0.17.0
- mcp-atlassian (PyPI): affected all versions; fixed in 0.17.0
- mcp-atlassian (PyPI): affected all versions; fixed in 0.17.0

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-27826/ (Markdown: https://insights.sbomify.com/CVE-2026-27826/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-27826
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27826
- OSV: https://osv.dev/vulnerability/CVE-2026-27826

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-27826/
Summaries are generated and may contain mistakes; the official description above is the record.