CVE-2026-48710

MEDIUM EPSS 69.8%
Published May 26, 20261mo ago · Modified Jun 23, 20261w ago
6.5 CVSS 3.1
Medium
Find Similar
Published May 26, 2026 1mo ago
Last Modified Jun 23, 2026 1w ago

Description

Starlette is a lightweight ASGI framework/toolkit. Prior to version 1.0.1, the HTTP `Host` request header was not validated before being used to reconstruct `request.url`. Because the routing algorithm relies on the raw HTTP path while `request.url` is rebuilt from the `Host` header, a malformed header could make `request.url.path` differ from the path that was actually requested. Middleware and endpoints that apply security restrictions based on `request.url` (rather than the raw `scope` path) could therefore be bypassed. Users should upgrade to a version greater than or equal to version 1.0.1, which validates the `Host` header against the grammar of RFC 9112 §3.2 / RFC 3986 §3.2.2 when constructing `request.url` and falls back to `scope["server"]` for malformed values.

CVSS Details

Base Score
6.5
Exploitability
3.9
Impact
2.5
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction None
Scope Unchanged
Confidentiality Low
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
69.8% percentile
Exploit & Patch Status
Public Exploit Known
Patch Available

Weaknesses 2

CWE-1289
CWE-444

Affected Products 1

VendorProductVersionRange
encodestarlette*≥0.8.3  –  <1.0.1

References 10

  • access.redhat.com https://access.redhat.com/security/cve/CVE-2026-48710
  • badhost.org https://badhost.org
    MitigationThird Party Advisory
  • bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=2481742
  • github.com https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6
    Patch
  • github.com https://github.com/Kludex/starlette/security/advisories/GHSA-86qp-5c8j-p5mr
    Vendor Advisory
  • github.com https://github.com/pypa/advisory-database/tree/main/vulns/starlette/PYSEC-2026-161.yaml
    Third Party Advisory
  • ostif.org https://ostif.org/disclosing-the-badhost-vulnerability-in-starlette
    MitigationThird Party Advisory
  • security.access.redhat.com https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-48710.json
  • secwest.net https://www.secwest.net/starlette
    ExploitMitigationThird Party Advisory
  • x41-dsec.de https://www.x41-dsec.de/lab/advisories/x41-2026-002-starlette
    ExploitMitigationThird Party Advisory

Remediation

  • github.com https://github.com/Kludex/starlette/commit/764dab0dcfb9033d75442d7a359645c9f94648c6
    Patch