# CVE-2026-77242: MCP Atlassian: Incomplete fix for CVE-2026-27826: DNS rebinding bypasses SSRF validation (validated IP not pinned)

> Attackers can bypass SSRF protections via DNS rebinding to access internal or metadata endpoints in the MCP Atlassian server.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/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:** 22 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-72fm-whvq-jghf

## What is CVE-2026-77242?

CVE-2026-77242 is a high-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 22 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). Prior to 0.22.0, validate_url_for_ssrf checks a hostname's resolved addresses, but Requests and urllib3 resolve the hostname again when connecting. A caller can use a short-lived DNS answer that is public during validation and private during connection, preserving unauthenticated access to internal or metadata endpoints despite the earlier CVE-2026-27826 remediation. The advisory traces the vulnerable input and processing flow through validate_url_for_ssrf, _check_dns_resolution, socket.getaddrinfo, and _make_ssrf_safe_hook, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.

Weakness: CWE-918 (Server-Side Request Forgery), CWE-367 (Time-of-check Time-of-use (TOCTOU) Race Condition)

## Which versions are affected by CVE-2026-77242?

It affects 1 product.


Products: Mcp-Atlassian Mcp Atlassian.

## How do I fix CVE-2026-77242?

No fix has been published for CVE-2026-77242 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-77242 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77242 exists.

## Other vulnerabilities in sooperset mcp-atlassian

- [CVE-2026-77244](https://insights.sbomify.com/CVE-2026-77244/): [mcp-atlassian] Authentication bypass in HTTP transport: AtlassianOpaqueTokenVerifier accepts any non-empty token (critical 10.0)
- [CVE-2026-77254](https://insights.sbomify.com/CVE-2026-77254/): MCP Atlassian: Unauthenticated HTTP MCP requests can use globally configured Jira and Confluence credentials (critical 9.1)
- [CVE-2026-27825](https://insights.sbomify.com/CVE-2026-27825/): MCP Atlassian has an arbitrary file write leading to arbitrary code execution via unconstrained download_path in confluence_download_attachment (critical 9.1)
- [CVE-2026-77243](https://insights.sbomify.com/CVE-2026-77243/): MCP Atlassian: ENABLED_TOOLS / Toolset authorization bypass (high 8.8)
- [CVE-2026-77274](https://insights.sbomify.com/CVE-2026-77274/): MCP Atlassian: SSRF Protection Bypass (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77242 and fix it if it is affected.

What it is: CVE-2026-77242 is a high-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 22 Sep 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77242 exists.

Affected product: sooperset mcp-atlassian. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-77242/ (Markdown: https://insights.sbomify.com/CVE-2026-77242/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77242
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77242
- OSV: https://osv.dev/vulnerability/CVE-2026-77242

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77242/
Summaries are generated and may contain mistakes; the official description above is the record.