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.
Fix
Patch, vendor advisory and mitigation references on NVD 3
- https://github.com/Kludex/starlette/commit/fd53168a7767b6b55ba5af787fd88f49e33cabc5 Patch
- https://github.com/Kludex/starlette/pull/3287 Patch
- https://github.com/Kludex/starlette/security/advisories/GHSA-wqp7-x3pw-xc5r Mitigation, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 7.5 · encodeNVD modified 2026-10-26 11:10
Affected (CPE criteria) 1
cpe:2.3:a:encode:starlette:*:*:*:*:*:python:*:*
References 11
- https://github.com/Kludex/starlette/commit/fd53168a7767b6b55ba5af787fd88f49e33cabc5 Patch
- https://github.com/Kludex/starlette/pull/3287 Patch
- https://github.com/Kludex/starlette/releases/tag/1.1.0 Release Notes
- https://github.com/Kludex/starlette/security/advisories/GHSA-wqp7-x3pw-xc5r Mitigation, Vendor Advisory
- https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-2281.yaml
- https://access.redhat.com/errata/RHSA-2026:30087
- https://access.redhat.com/errata/RHSA-2026:30088
- https://access.redhat.com/errata/RHSA-2026:30089
- https://access.redhat.com/security/cve/CVE-2026-48818
- https://bugzilla.redhat.com/show_bug.cgi?id=2490020
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48818.json