Indico up to 3.3.9 Environment Variable http_proxy/https_proxy toctou

Summaryinfo

A vulnerability was found in Indico up to 3.3.9. It has been classified as critical. Affected is an unknown function of the component Environment Variable Handler. This manipulation of the argument http_proxy/https_proxy causes toctou. The identification of this vulnerability is CVE-2026-25738. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Indico up to 3.3.9. It has been declared as critical. Affected by this vulnerability is an unknown code block of the component Environment Variable Handler. The manipulation of the argument http_proxy/https_proxy with an unknown input leads to a toctou vulnerability. The CWE definition for the vulnerability is CWE-367. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Indico is an event management system that uses Flask-Multipass, a multi-backend authentication system for Flask. Versions prior to 3.3.10 are vulnerable to server-side request forgery. Indico makes outgoing requests to user-provides URLs in various places. This is mostly intentional and part of Indico's functionality but is never intended to let users access "special" targets such as localhost or cloud metadata endpoints. Users should upgrade to version 3.3.10 to receive a patch. Those who do not have IPs that expose sensitive data without authentication (typically because they do not host Indico on AWS) are not affected. Only event organizers can access endpoints where SSRF could be used to actually see the data returned by such a request. For those who trust their event organizers, the risk is also very limited. For additional security, both before and after patching, one may also use the common proxy-related environment variables (in particular `http_proxy` and `https_proxy`) to force outgoing requests to go through a proxy that limits requests in whatever way you deem useful/necessary. These environment variables would need to be set both on the indico-uwsgi and indico-celery services.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-25738 since 02/05/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 3.3.10 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 70d341826116fac5868719a6133f2c26d9345137 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• Indico

Version

• 3.3.0
• 3.3.1
• 3.3.2
• 3.3.3
• 3.3.4
• 3.3.5
• 3.3.6
• 3.3.7
• 3.3.8
• 3.3.9

License

• open-source

Website

• Product: https://github.com/indico/indico/

CPE 2.3info

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CPE 2.2info

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