Medium severity · published Sep 4, 2026
CVE-2026-9186
Langflow is vulnerable to stored cross-site scripting and IP spoofing due to unsanitized Markdown rendering and untrusted proxy header trust
6.5
CVSS
0.4%
EPSS
No
On KEV
Description
IBM Langflow OSS 1.0.0 through 1.11.2 allows remote authenticated attackers to bypass localhost-only MCP configuration installation by spoofing X-Forwarded-For: 127.0.0.1 header, enabling arbitrary writes to IDE config files (~/.cursor/mcp.json, etc.).
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 32% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LO
Langflow OSS · IBM
1.0.0 through 1.11.2 · source: vendor
LA
Langflow · Langflow
1.0.0 before 1.11.3 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-9186
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-9186
Patch
https://www.ibm.com/support/pages/node/7285646
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