CVE-2026-48818

Starlette: SSRF and NTLM credential theft via UNC paths in StaticFiles on Windows

Published Jun 17, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
Description
Starlette is a lightweight ASGI framework/toolkit. In versions 1.0.1 and earlier, StaticFiles on Windows is vulnerable to SSRF. An UNC path such as \\attacker.com\share can cause os.path.realpath to initiate an outbound SMB connection before the path is rejected, exposing the service account’s NTLMv2 credentials for offline cracking or relay even though the HTTP response is only a 404. The issue affects default follow_symlink=False deployments, including frameworks built on Starlette such as FastAPI; POSIX systems and follow_symlink=True are unaffected. The issue is fixed in 1.1.0.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-wqp7-x3pw-xc5r Starlette: SSRF and NTLM credential theft via UNC paths in StaticFiles on Windows
History
Type Values Removed Values Added
First Time appeared Kludex
Kludex starlette
Vendors & Products Kludex
Kludex starlette
Type Values Removed Values Added
Description Starlette is a lightweight ASGI framework/toolkit. In versions 1.0.1 and earlier, StaticFiles on Windows is vulnerable to SSRF. An UNC path such as \\attacker.com\share can cause os.path.realpath to initiate an outbound SMB connection before the path is rejected, exposing the service account’s NTLMv2 credentials for offline cracking or relay even though the HTTP response is only a 404. The issue affects default follow_symlink=False deployments, including frameworks built on Starlette such as FastAPI; POSIX systems and follow_symlink=True are unaffected. The issue is fixed in 1.1.0.
Title Starlette: SSRF and NTLM credential theft via UNC paths in StaticFiles on Windows
Weaknesses CWE-918
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Aug 4, 2026, 5:45 PM
Reserved
May 22, 2026, 8:57 PM
Status
Modified
Published
Jun 17, 2026, 7:18 PM
Modified
Oct 26, 2026, 11:10 AM
Severity
Important
Public date
Jun 17, 2026, 5:50 PM