Thelia up to 2.6.1 Smarty Template checkTemplate special elements in template engine

Summaryinfo

A vulnerability described as critical has been identified in Thelia up to 2.6.1. Impacted is the function checkTemplate of the component Smarty Template Handler. Such manipulation leads to special elements in template engine. This vulnerability is referenced as CVE-2026-103537. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability was found in Thelia up to 2.6.1. It has been rated as critical. Affected by this issue is the function checkTemplate of the component Smarty Template Handler. The manipulation with an unknown input leads to a special elements in template engine vulnerability. Using CWE to declare the problem leads to 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. Impacted is confidentiality, integrity, and availability. CVE summarizes:

Thelia 2.6.1 contains an absolute path traversal vulnerability in its Smarty template handling that enables SSTI and remote code execution. The `checkTemplate()` validation restricts relative directory traversal sequences such as `../` but does not reject absolute paths, allowing an authorized user to supply an arbitrary filesystem path as a template. Smarty then loads and compiles the referenced file without an effective security policy, so depending on filesystem layout and deployment configuration, template code in the file can be executed with the web server's privileges.

The advisory is shared for download at kb.cert.org. This vulnerability is handled as CVE-2026-103537 since 09/30/2026. The exploitation is known to be easy. The attack may be launched remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 10/12/2026). The MITRE ATT&CK project declares the attack technique as T1221.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Name

• Thelia

Version

• 2.6.0
• 2.6.1

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CPE 2.2info

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