# CVE-2026-73497: MCP Atlassian: DNS-rebinding TOCTOU bypass of the SSRF fix (CVE-2026-27826)

> Unauthenticated attackers can bypass SSRF protections via DNS rebinding to access cloud metadata or internal services in MCP Atlassian.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 14 Sep 2026
- **Updated:** 15 Sep 2026
- **Also known as:** GHSA-489g-7rxv-6c8q

## What is CVE-2026-73497?

CVE-2026-73497 is a medium-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). From 0.17.0 until 0.22.0, validate_url_for_ssrf resolves the attacker-controlled X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url header host once at middleware time, but the outbound request is built with the raw hostname and resolves it again at connection time with no IP pinning. An attacker-controlled DNS-rebinding name can return a public IP during validation and 169.254.169.254 or another internal IP during connection, enabling unauthenticated server-side requests to cloud metadata or internal services. The flaw spans src/mcp_atlassian/utils/urls.py, src/mcp_atlassian/servers/main.py, and src/mcp_atlassian/servers/dependencies.py; validate_url_for_ssrf returns only a verdict rather than a pinned IP, UserTokenMiddleware processes the attacker-controlled headers before fetcher creation, and the Jira and Confluence fetchers use the raw hostname. This issue is fixed in version 0.22.0.

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

## Which versions are affected by CVE-2026-73497?

2 open source packages ship an affected version, including mcp-atlassian.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `mcp-atlassian` | PyPI | All versions | 0.22.0 |
| `mcp-atlassian` | PyPI | All versions | 0.22.0 |

## How do I fix CVE-2026-73497?

Upgrade mcp-atlassian to 0.22.0 or later.

## Is CVE-2026-73497 being exploited?

There is no known exploitation of CVE-2026-73497 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73497 and fix it if it is affected.

What it is: CVE-2026-73497 is a medium-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 14 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-73497 in the wild and no public exploit code.

Affected packages and fixed versions:
- mcp-atlassian (PyPI): affected all versions; fixed in 0.22.0
- mcp-atlassian (PyPI): affected all versions; fixed in 0.22.0

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-2026-73497/ (Markdown: https://insights.sbomify.com/CVE-2026-73497/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73497
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73497
- OSV: https://osv.dev/vulnerability/CVE-2026-73497

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73497/
Summaries are generated and may contain mistakes; the official description above is the record.