CVE-2021-29261 in Svelte Extension
Summary
by MITRE • 04/05/2021
The unofficial Svelte extension before 104.8.0 for Visual Studio Code allows attackers to execute arbitrary code via a crafted workspace configuration.
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Analysis
by VulDB Data Team • 04/10/2021
The vulnerability identified as CVE-2021-29261 affects the unofficial Svelte extension for Visual Studio Code, specifically versions prior to 104.8.0. This represents a critical security flaw that enables remote code execution through malicious workspace configuration files. The issue stems from insufficient input validation and sanitization within the extension's handling of workspace settings, creating an attack surface where untrusted data can be interpreted as executable commands. The vulnerability is particularly concerning because it leverages the trusted environment of a code editor to execute arbitrary code, potentially allowing attackers to gain full system access or compromise development environments.
The technical implementation of this vulnerability involves the extension's failure to properly validate workspace configuration parameters that are loaded during the development session. When a user opens a workspace containing maliciously crafted configuration entries, the extension processes these entries without adequate sanitization checks. This allows attackers to inject code that gets executed within the context of the Visual Studio Code process, which typically runs with elevated privileges due to its integration with the development environment. The flaw operates at the intersection of insecure deserialization and command injection patterns, where user-supplied configuration data is directly interpreted as executable instructions rather than being properly validated or escaped.
From an operational impact perspective, this vulnerability poses significant risks to software development teams and organizations relying on Visual Studio Code for their development workflows. Attackers can exploit this weakness by crafting malicious workspace files that appear legitimate to unsuspecting developers, potentially leading to complete system compromise. The attack vector is particularly dangerous because it requires no special privileges to initiate and can be delivered through common attack methods such as phishing emails containing malicious workspace files or compromised repositories. The vulnerability affects the entire development ecosystem since Visual Studio Code extensions are frequently shared and reused across teams, making the attack surface potentially large and widespread.
Organizations should immediately update to version 104.8.0 or later of the Svelte extension to mitigate this vulnerability, as this release includes proper input validation and sanitization measures. Additional defensive strategies include implementing strict workspace file validation policies, educating developers about the risks of opening workspace files from untrusted sources, and conducting regular security audits of installed extensions. The vulnerability aligns with CWE-74 and CWE-94 categories, representing improper neutralization of special elements used in data queries and improper validation of a resource identifier. From an ATT&CK framework perspective, this vulnerability maps to T1059.001 (Command and Scripting Interpreter) and T1203 (Exploitation for Client Execution), demonstrating how attackers can leverage development tools to achieve their objectives. Security teams should also consider implementing network monitoring to detect suspicious extension activity and maintain updated threat intelligence feeds to identify potential exploitation attempts.