# CVE-2026-77261: MCP Atlassian: SSRF redirect protection missing for basic-auth and OAuth authentication branches

> Attackers can force the MCP Atlassian server to access internal resources via redirects when using basic-auth or OAuth, bypassing SSRF protections.

- **Severity:** High 7.1 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 22 Sep 2026
- **Updated:** 23 Sep 2026
- **Also known as:** GHSA-6529-c226-h328, PYSEC-2026-4085

## What is CVE-2026-77261?

CVE-2026-77261 is a high-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 22 Sep 2026. Any signed-in user can exploit it over the 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 0.22.0, _make_ssrf_safe_hook is omitted from JiraFetcher and ConfluenceFetcher sessions created through the basic-auth and oauth_pat branches. If an attacker-controlled or compromised configured Atlassian instance returns a redirect to an internal address, those sessions can follow the redirect without revalidating its destination. This issue is fixed in version 0.22.0.

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

## Which versions are affected by CVE-2026-77261?

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 | 0.22.0 |
| `mcp-atlassian` | PyPI | All versions | 0.22.0 |
| `mcp-atlassian` | PyPI | All versions | 0.22.0 |

Products: Mcp-Atlassian Mcp Atlassian.

## How do I fix CVE-2026-77261?

Upgrade mcp-atlassian to 0.22.0 or later.

## Is CVE-2026-77261 being exploited?

There is no known exploitation of CVE-2026-77261 in the wild and no public exploit code.

## 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-2026-77261 and fix it if it is affected.

What it is: CVE-2026-77261 is a high-severity server-side request forgery vulnerability in sooperset mcp-atlassian, published on 22 Sep 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-77261 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
- 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-2026-77261/ (Markdown: https://insights.sbomify.com/CVE-2026-77261/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77261
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77261
- OSV: https://osv.dev/vulnerability/CVE-2026-77261

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77261/
Summaries are generated and may contain mistakes; the official description above is the record.