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01 Record

CVE-2026-77258

MCP Atlassian: Arbitrary file read/exfiltration via upload_attachment missing validate_safe_path()

HighPUBLISHEDCNA: GitHub_M
CNA base score7.7 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
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02 Description

MCP Atlassian: Arbitrary file read/exfiltration via upload_attachment missing validate_safe_path()

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.37% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 31.1% of scored records. A rank, not a probability.
NVD base score
7.7 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
NVD analysis status
Analyzed. NVD last modified this record on 2026-09-29.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-09-22 17:39Z1 MO AGO
Last updated
2026-09-25 23:49Z1 MO AGO
Reserved
2026-08-20
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
High (CVSS 7.7)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Weaknesses
  • CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')Base
Data version
5.2
Document digest
4ab7487346296cd0b0189fa26027e80d2afb04ec79a48752635595de4e4629c2

05 Affected products

VendorProductVersionsPlatforms
soopersetmcp-atlassian< 0.22.0—

06 References