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Vulnerability Change Records for CVE-2021-41170

Change History

CVE Modified by GitHub, Inc. 11/15/2021 4:15:07 PM

Action Type Old Value New Value
Added CVSS V3.1

								
							
							
						
GitHub, Inc. AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Removed CVSS V3.1
GitHub, Inc. AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

								
						
Removed CVSS V3.1 Reason
A-No limiting factors

								
						
Removed CVSS V3.1 Reason
C-No limiting factors

								
						
Added CWE

								
							
							
						
GitHub, Inc. CWE-74
Changed Description
### Impact Versions prior 1.1.1 have allowed for passing in closures directly into the template engine. As a result values that are callable are executed by the template engine. The issue arises if a value has the same name as a method or function in scope and can therefore be executed either by mistake or maliciously. In theory all users of the package are affected as long as they either deal with direct user input or database values. A multi-step attack on is therefore plausible. ### Patches Version 1.1.1 has addressed this vulnerability. ```php $params = [ 'reverse' => fn($input) => strrev($input), // <-- no longer possible with version ~1.1.1 'value' => 'My website' ] TemplateFunctions::registerClosure('reverse', fn($input) => strrev($input)); // <-- still possible (and nicely isolated) Template::embrace('<h1>{{reverse(value)}}</h1>', $params); ``` ### Workarounds Unfortunately only working with hardcoded values is safe in prior versions. As this likely defeats the purpose of a template engine, please upgrade. ### References As a possible exploit is relatively easy to achieve, I will not share steps to reproduce the issue for now. ### For more information If you have any questions or comments about this advisory: * Open an issue in [our repo](https://github.com/sroehrl/neoan3-template)
neoan3-apps/template is a neoan3 minimal template engine. Versions prior to 1.1.1 have allowed for passing in closures directly into the template engine. As a result values that are callable are executed by the template engine. The issue arises if a value has the same name as a method or function in scope and can therefore be executed either by mistake or maliciously. In theory all users of the package are affected as long as they either deal with direct user input or database values. A multi-step attack on is therefore plausible. Version 1.1.1 has addressed this vulnerability. Unfortunately only working with hardcoded values is safe in prior versions. As this likely defeats the purpose of a template engine, please upgrade.