PHP2Shell : See if you’re affected with a free external attack surface scan. Click Here > 

Back
New CVE Detected

CVE-2026-77274 – SSRF Protection Bypass – mcp-atlassian < 0.22.0

Be the first to know when new zero-days emerge:

Subscribe to Email Alerts
Subscribe to RSS Feed

Summary

CVE-2026-77274 is a Server-Side Request Forgery (SSRF) protection bypass affecting mcp-atlassian, a Model Context Protocol (MCP) server that connects AI agents to Atlassian Jira and Confluence. Versions prior to 0.22.0 contain a URL-parsing inconsistency in the validate_url_for_ssrf function that lets an attacker craft a URL which passes SSRF validation as pointing to an external host while the underlying HTTP client actually connects to an internal or loopback address. The issue carries a CVSS v4.0 base score of 8.8 (High) and requires no authentication or user interaction.

Technical details

  • Root cause: validate_url_for_ssrf() parses URLs using Python’s urllib.parse.urlparse(), while the actual outbound request is made via the requests library’s Session, which interprets URL authority/userinfo syntax differently — creating a parser mismatch (backslash-before-userinfo confusion).
  • Trigger conditions: An attacker supplies a crafted URL (e.g., http://127.0.0.1:[email protected]) via the X-Atlassian-Jira-Url or X-Atlassian-Confluence-Url HTTP headers used in the header-based Jira/Confluence authentication flow. The validation layer evaluates the URL as pointing to the external host (www.baidu.com), while requests percent-encodes the backslash and routes the connection to the attacker-specified internal target (127.0.0.1:6666).
  • Attack vector: Network — no authentication and no user interaction are required; the attacker only needs the ability to reach the mcp-atlassian HTTP endpoint and set custom headers.
  • Impact: Successful exploitation allows the server process to make outbound requests to internal/loopback network resources that should be unreachable, enabling internal network reconnaissance, access to internal services, and potential exposure of sensitive data returned to the attacker (High confidentiality impact, Low integrity impact per the CVSS vector).

Affected software

  • Product: mcp-atlassian (vendor: sooperset)
  • Vulnerable versions: all versions prior to 0.22.0
  • Fixed version: 0.22.0

Severity

  • CVSS v4.0 Base Score: 8.8 (High)
  • Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
  • CWE-918: Server-Side Request Forgery (SSRF)

Mitigation and recommended actions

  • Immediate: Upgrade mcp-atlassian to version 0.22.0 or later, which fixes the URL-parsing inconsistency between the SSRF validation logic and the HTTP request layer.
  • If patching is not immediately possible:
    • Restrict network access to the mcp-atlassian HTTP endpoint to trusted clients only (e.g., via network segmentation, firewall rules, or an authenticating reverse proxy).
    • Strip or validate the X-Atlassian-Jira-Url and X-Atlassian-Confluence-Url headers at a gateway/proxy layer before they reach mcp-atlassian, disallowing userinfo/backslash characters in the authority component.
    • Monitor outbound traffic from the mcp-atlassian host for unexpected connections to loopback or internal address ranges.

References

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report

How IONIX’s External Exposure Management Platform Detects and Validates
Zero-Days to Shrink MTTR

1

Map your entire attack surface (continously)

IONIX uses multi-factor discovery methods, including DNS analysis, certificate mapping, metadata inspection, and more, to automatically map every internet-facing asset across your environment. This includes cloud instances, third-party platforms, shadow IT, and even forgotten infrastructure that traditional tools miss.

2

Monitor for new CVEs

Dozens of threat intel feeds using agentic technology are continuously analyzed to detect the appearance of proof-of-concept code, exploit kits, and indicators of active targeting. IONIX goes further by applying AI to proactively evaluate whether emerging vulnerabilities are likely to be exploited, even before PoCs go public.

3

Identify Potential External Exposures

Not all CVEs matter. IONIX filters vulnerabilities by asking attacker-centric questions: Can it be reached from the internet? Does it require authentication? Is it being exploited in the wild? This dramatically reduces noise and focuses teams on threats that can actually be weaponized.

4

Create Safe, Scalable Exploit Validations

IONIX transforms real-world PoCs into safe, non-intrusive test payloads that can be run in production environments without disruption. These simulations are precisely targeted to the systems that are vulnerable, ensuring rapid validation without unnecessary load.

5

Execute Exploit Validations

By combining context about software stack, versioning, exposure status, and reachability, IONIX ensures that only the right payloads are executed against the right assets, maximizing efficiency and minimizing risk.

6

Drive Fast and Actionable Remediation

Results are routed through integrations with ticketing, SOAR, and SIEM tools. Issues are written in plain language, bundled into remediation clusters, and prioritized based on asset criticality, exploitability, and blast radius. This shortens mean time to remediation (MTTR) and empowers teams to act with confidence.

Are you exposed?

Get a free report of your organization’s exposure to this CVE and threat

  • Mapping of all Assets with this Technology
  • Identification of potentially exposed assets to this CVE
  • Confirmation of verified exploitable assets
Get Exposure Report
Close

Subscribe to Threat Center RSS

Copy/paste the link below into your preferred RSS reader or follow these instructions to subscribe to Slack alerts.

Open RSS feedSlack setup instructions

Close

Get Real-Time CVE Alerts to Your Email

Be the first to know when new zero-days emerge