CVE-2026-48710 — Kludex starlette

What is CVE-2026-48710?

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.

The record classifies CVE-2026-48710 under weakness class CWE-444. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 156 days ago.

Severity and exploitation probability

CVSS v3.1 base score: 6.5 — MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
EPSS (FIRST): 7.0% probability of exploitation in the next 30 days, higher than 94.0% of all scored CVEs
CISA KEV: Listed since 2026-09-02, federal remediation deadline 2026-09-16
Threadlinqs priority: 9/10 — CISA KEV-listed, which Threadlinqs floors at 9
Published: 2026-05-26, last modified 2026-10-01

Is CVE-2026-48710 being exploited?

CISA added CVE-2026-48710 to the Known Exploited Vulnerabilities catalog on 2026-09-02, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2026-09-16 under BOD 22-01. Weaponised exploit code for CVE-2026-48710 is publicly available. 6 public proof-of-concept repositories are tracked for this identifier. A ProjectDiscovery Nuclei detection template exists (http/cves/2026/CVE-2026-48710.yaml). It currently carries a trending score of 49 in the Threadlinqs vulnerability feed.

eris-ths/supply-chain-guard (github)
xtremebeing/starlette-host-header-lab (github)
Bhanunamikaze/BadHost-CVE-2026-48710-Exploit (github)
sb-ox/repro-OXDEV-77637-uv-workspace (github)
CuteeCat/CVE-2026-48710 (github)
trickest/cve (trickest)

Affected products and versions

Kludex: starlette

How to fix CVE-2026-48710

Because CVE-2026-48710 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2026-09-16. No vendor patch reference has been recorded for CVE-2026-48710 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

Threat activity tracking CVE-2026-48710

7 tracked threats in the Threadlinqs corpus reference CVE-2026-48710, either in the campaign’s CVE list or as an indicator on the campaign record.

PoeLLM (Canto Incognito) malware infects exposed AI servers (LiteLLM, Ollama, Gotenberg, Gitea, Ivanti Sentry) in cryptomining attacks - CVE-2026-42271, CVE-2026-48710 — HIGH · 2026-10-07
GTIG: AI-Era Vulnerability Discovery and Exploitation Surge — In-the-Wild Exploitation of BeyondTrust CVE-2026-1731, LiteLLM CVE-2026-42271 and Langflow CVE-2026-5027 — CRITICAL · 2026-09-30
Qilin-Linked Campaign Exploits MCP Gateway and LLM Framework Flaws (CVE-2026-59822, CVE-2026-42271, CVE-2026-48710) for RCE and Cryptomining — CRITICAL · 2026-08-28
LiteLLM Proxy Authentication Bypass via Host Header Injection (CVE-2026-49468) — CRITICAL · 2026-06-17
CVE-2026-42271: LiteLLM AI Gateway OS Command Injection via MCP Test Endpoints, Chained to Unauthenticated RCE with CVE-2026-48710 (CISA KEV, Active Exploitation) — CRITICAL · 2026-06-09
CVE-2026-42271: LiteLLM MCP Server Command Injection Under Active Exploitation, Chained with CVE-2026-48710 (Starlette BadHost) for Unauthenticated RCE — CRITICAL · 2026-06-09
BadHost CVE-2026-48710 — Starlette HTTP Host Header Authentication Bypass Affecting FastAPI/AI Infrastructure (MCP, vLLM, LiteLLM) — CRITICAL · 2026-05-27

Sources

Enriched from CVE.org, FIRST EPSS, CISA KEV, public proof-of-concept repositories, ProjectDiscovery Nuclei. Last verified by Threadlinqs on 2026-10-10.

Vendor advisory and patch

github.com

Other references

Showing 6 of 7 recorded references.