CVE-2020-15233

OAuth2 Redirect URL validity does not respect query parameters and character casing for loopback addresses

MEDIUM
4.8
CVSS Score
Published: October 2, 2020 at 08:40 PM UTC
Updated: June 17, 2026 at 02:56 AM UTC
1 product affected across 1 vendorFosite

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Severity
MEDIUM4.8
Exploit prediction
EPSS 0.8%

Description

ORY Fosite is a security first OAuth2 & OpenID Connect framework for Go. In Fosite from version 0.30.2 and before version 0.34.1, there is an issue in which an an attacker can override the registered redirect URL by performing an OAuth flow and requesting a redirect URL that is to the loopback adapter. Attackers can provide both custom URL query parameters to their loopback redirect URL, as well as actually overriding the host of the registered redirect URL. These attacks are only applicable in scenarios where the attacker has access over the loopback interface. This vulnerability has been patched in ORY Fosite v0.34.1.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 0.34.10.30.2 ≤ v < 0.34.1
Affected range stops below 0.34.1, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
HIGH
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-20CWE-601

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