Executive Summary

CVE-2026-33149 is a Host Header Injection vulnerability in the Tandoor Recipes application, specifically affecting version 2.5.3. The root cause is that the application sets Django's ALLOWED_HOSTS configuration to '*', which disables validation of the HTTP Host header. This means the server accepts any Host header value sent in requests.

The application uses Django's request.build_absolute_uri() method to generate absolute URLs in various contexts such as invite link emails, API pagination, and OpenAPI schema generation. Because the Host header is not validated, an attacker can send requests with a crafted Host header to manipulate these generated URLs.

The most critical impact is invite link poisoning: when an admin creates an invite, the invite email contains a link that points to the attacker's server instead of the real application. If a victim clicks this link, the invite token is sent to the attacker, who can then use it to hijack account provisioning on the legitimate server.

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Impact Analysis

This vulnerability can have serious security impacts including unauthorized access and manipulation of user account invitations.

• Invite link poisoning allows attackers to intercept invite tokens by sending victims links pointing to attacker-controlled domains.
• Attackers can use stolen invite tokens to hijack account provisioning on the legitimate application.
• In environments using caching proxies, a single poisoned request can corrupt cached responses for all users, amplifying the attack's reach.
• The vulnerability compromises confidentiality and integrity by allowing attackers to gain unauthorized access and manipulate sensitive tokens.

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Detection Guidance

This vulnerability can be detected by sending HTTP requests to the Tandoor Recipes application with a forged Host header and observing if the server accepts it without validation.

You can test this by crafting requests with different Host headers and checking if the application-generated URLs (such as invite links, API pagination URLs, or OpenAPI schema URLs) reflect the attacker-controlled Host header.

• Use curl to send a request with a custom Host header, for example: curl -H "Host: attacker.com" http://your-tandoor-recipes-server/
• Check API pagination responses for next and previous URLs containing the forged Host header.
• Request the OpenAPI schema endpoint and verify if the server URLs include the attacker-controlled Host.
• Trigger an invite email by sending an invite request with a poisoned Host header and verify if the invite link in the email points to the attacker domain.

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Mitigation Strategies

The immediate mitigation step is to properly configure the Django ALLOWED_HOSTS setting to restrict accepted Host headers to trusted domain names instead of using the wildcard '*'.

By setting ALLOWED_HOSTS to a list of valid hostnames, the application will reject requests with unrecognized Host headers, preventing Host header injection.

Additionally, monitor and audit invite emails and API responses to ensure that generated URLs use only trusted hosts.

Since no patched version is available at the time of reporting, configuration changes are the primary defense.

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Compliance Impact

The vulnerability allows an attacker to hijack invite tokens by poisoning invite links sent via email, leading to unauthorized access and compromise of user account security.

Such unauthorized access and compromise of confidentiality and integrity of user data can negatively impact compliance with data protection regulations like GDPR and HIPAA, which require safeguarding personal and sensitive information against unauthorized access.

However, the provided information does not explicitly mention compliance impacts or specific regulatory considerations.

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