netbox-community NetBox up to 4.6.x Custom links clean_html COOKIES[sessionid] special elements in template engine

Summaryinfo

A vulnerability identified as critical has been detected in netbox-community NetBox up to 4.6.x. This impacts the function clean_html of the component Custom links. Performing a manipulation of the argument COOKIES[sessionid] results in special elements in template engine. This vulnerability was named CVE-2026-104073. The attack may be initiated remotely. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in netbox-community NetBox up to 4.6.x. This affects the function clean_html of the component Custom links. The manipulation of the argument COOKIES[sessionid] with an unknown input leads to a special elements in template engine vulnerability. CWE is classifying the issue as CWE-1336. The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

NetBox versions 2.9.5 before 4.7.0 contain a server-side template injection vulnerability that allows a low-privileged user with the "Can add custom links" permission to steal session cookies and API tokens of other users by exposing the raw Django HttpRequest object to the Jinja2 template context. Attackers can craft a custom link template embedding request.COOKIES['sessionid'] or a user's API token into an img src URL, which bypasses the clean_html sanitizer and auto-exfiltrates the victim's credentials to an attacker-controlled host when a privileged user views the object, enabling full account takeover.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-104073 since 10/01/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1221 according to MITRE ATT&CK.

Upgrading to version 4.7.0 eliminates this vulnerability.

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Productinfo

Vendor

• netbox-community

Name

• NetBox

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6

Website

• Product: https://github.com/netbox-community/netbox/

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