CVE-2026-77242 (GCVE-0-2026-77242)
Vulnerability from cvelistv5 – Published: 2026-09-22 17:58 – Updated: 2026-09-22 18:49
VLAI
EPSS
VEX
Title
MCP Atlassian: Incomplete fix for CVE-2026-27826: DNS rebinding bypasses SSRF validation (validated IP not pinned)
Summary
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.
Severity
7.5 (High)
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-22 18:48 UTC
CWE
Assigner
References
4 references
| URL | Tags |
|---|---|
| https://github.com/sooperset/mcp-atlassian/securi… | x_refsource_CONFIRM |
| https://github.com/sooperset/mcp-atlassian/pull/1448 | x_refsource_MISC |
| https://github.com/sooperset/mcp-atlassian/commit… | x_refsource_MISC |
| https://github.com/sooperset/mcp-atlassian/releas… | x_refsource_MISC |
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| sooperset | mcp-atlassian |
Affected:
< 0.22.0
|
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
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