CVE-2026-77274 json
MCP Atlassian: SSRF Protection Bypass
published 2026-09-22 47 d ago modified 2026-10-01 38 d ago also GHSA-hgcf-4mq8-5266 , PYSEC-2026-4096 , EUVD-2026-84649
- cvss
- 8.2
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 26%
- public exploits
- 0
- none known
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 has a backslash authority confusion because it interprets the authority differently from the Requests connection layer in the header-based Jira and Confluence URL authentication flow. A crafted URL can validate as an external hostname while the HTTP client connects to an internal host, permitting server-side requests to protected network resources. This issue is fixed in version 0.22.0.
Patch / fix
- pypi mcp-atlassian 0.22.0
- mcp-atlassian mcp_atlassian 0.22.0
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 47 d ago
Exploit prediction
0.33% chance of exploitation in the next 30 days, higher than 26% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-hgcf-4mq8-5266 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.8 | 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 |
| CNA | 4.0 | 8.8 | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
| NVD | 3.1 | 8.2 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | mcp-atlassian | <0.22.0 |
0.22.0 |
Affected products
- sooperset mcp-atlassian
Classification
- Weakness
-
- CWE-918 Server-Side Request Forgery
References
-
github.com
/sooperset/mcp-atlassian/pull/1448
web, issue-tracking, patch
-
github.com
/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460
web, patch
-
github.com
/sooperset/mcp-atlassian/security/advisories/GHSA-hgcf-4mq8-5266
exploit, web, vendor-advisory
-
github.com
/sooperset/mcp-atlassian/releases/tag/v0.22.0
web, release-notes
-
nvd.nist.gov
/vuln/detail/CVE-2026-77274
advisory
-
github.com
/sooperset/mcp-atlassian
package
-
pypi.org
/project/mcp-atlassian
package
-
github.com
/advisories/GHSA-hgcf-4mq8-5266
advisory
Sources
- CVE List CVE-2026-77274
- GitHub Advisory GHSA-hgcf-4mq8-5266
- NVD CVE-2026-77274
- OSV PYSEC-2026-4096
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.