CVE-2026-48818
CVE-2026-48818 — Starlette: SSRF and NTLM credential theft via UNC paths in StaticFiles on Windows
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.
Published Updated Sources: cvelistV5, GitHub_M
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.
Exploitation
Unreported
no source claims exploitation
EPSS
0%
chance of exploitation in 30 days
CVSS base
7.5
HIGH
CISA SSVC assessment
Three decision points CISA publishes for the CVEs it assesses · SSVC 2.0.3. A stakeholder decision, not a severity score.
Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script all four kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component
Affected scope
The catalog records vendors and products as separate lists, not pairs, so which product belongs to which vendor is not something this page can say.
Products (11)
Every base score collected
Sources score independently and disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Source |
|---|---|---|---|---|---|
| 7.5 | CVSS 3.1 | HIGH | — | — | cvelistV5 |
Weakness & attack patterns
- CWE-918
Detection
Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.
- Search application, proxy, and WAF logs for requests touching /toolkit.
References
11 on the record
- github.com/Kludex/starlette/security/advisories/GHSA-wqp7-x3pw-xc5r
x_refsource_CONFIRM
- github.com/Kludex/starlette/pull/3287
x_refsource_MISC
- github.com/Kludex/starlette/commit/fd53168a7767b6b55ba5af787fd88f49e33cabc5
x_refsource_MISC
- github.com/Kludex/starlette/releases/tag/1.1.0
x_refsource_MISC
- github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-2281.yaml
x_refsource_MISC
- access.redhat.com/security/cve/CVE-2026-48818
vdb-entry, x_refsource_REDHAT
- bugzilla.redhat.com/show_bug.cgi?id=2490020
issue-tracking, x_refsource_REDHAT
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48818.json
x_sadp-csaf-vex
Elsewhere on this site
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.