Improper Validation in Starlette Framework Affects URL Rebuilding
CVE-2026-48710
Key Information:
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What is CVE-2026-48710?
CVE-2026-48710 is a critical vulnerability affecting the Starlette framework, a lightweight ASGI toolkit utilized for building web applications and APIs in Python. This vulnerability arises from improper validation of the HTTP Host request header before reconstructing the request.url, a key component in the routing algorithm. When a malformed header is provided, it can result in discrepancies between the actual requested path and the reconstructed URL. Because security mechanisms that depend on request.url could be bypassed, organizations utilizing this framework face heightened risks for potential unauthorized access or exploitation. The vulnerability was addressed in version 1.0.1, which introduced validation measures to ensure the integrity of the Host header against established RFC standards.
Potential impact of CVE-2026-48710
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Bypassing Security Restrictions: Attackers may exploit this vulnerability to circumvent security measures that rely on the validity of
request.url, potentially leading to unauthorized access to sensitive endpoints or data. -
Increased Attack Surface: The improper URL reconstruction creates an increased attack surface, allowing malicious actors to manipulate requests more freely, which could lead to further vulnerabilities being exploited within the application.
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Reputational and Financial Risks: Organizations affected by this vulnerability may suffer significant reputational damage and financial losses due to breaches or service disruptions, especially if personal data or sensitive information is compromised.
Affected Version(s)
starlette < 1.0.1
Exploit Proof of Concept (PoC)
PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.