deno up to 2.1.12/2.2.12 Environment Variable deno.env.toObject insertion of sensitive information into sent data

Summaryinfo

A vulnerability categorized as critical has been discovered in deno up to 2.1.12/2.2.12. Affected is the function deno.env.toObject of the component Environment Variable Handler. Executing a manipulation can lead to insertion of sensitive information into sent data. This vulnerability is registered as CVE-2025-48934. It is possible to launch the attack remotely. Furthermore, an exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability was found in deno up to 2.1.12/2.2.12. It has been declared as critical. This vulnerability affects the function deno.env.toObject of the component Environment Variable Handler. The manipulation with an unknown input leads to a insertion of sensitive information into sent data vulnerability. The CWE definition for the vulnerability is CWE-201. The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to versions 2.1.13 and 2.2.13, the `Deno.env.toObject` method ignores any variables listed in the `--deny-env` option of the `deno run` command. When looking at the documentation of the `--deny-env` option this might lead to a false impression that variables listed in the option are impossible to read. Software relying on the combination of both flags to allow access to most environment variables except a few sensitive ones will be vulnerable to malicious code trying to steal secrets using the `Deno.env.toObject()` method. Versions 2.1.13 and 2.2.13 contains a patch.

The advisory is shared for download at github.com. This vulnerability was named CVE-2025-48934 since 05/28/2025. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. Technical details and also a exploit are known. The MITRE ATT&CK project declares the attack technique as T1592.

It is declared as proof-of-concept.

Upgrading to version 2.1.13 or 2.2.13 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2025-16913). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

• deno

Version

• 2.1.0
• 2.1.1
• 2.1.2
• 2.1.3
• 2.1.4
• 2.1.5
• 2.1.6
• 2.1.7
• 2.1.8
• 2.1.9
• 2.1.10
• 2.1.11
• 2.1.12
• 2.2.0
• 2.2.1
• 2.2.2
• 2.2.3
• 2.2.4
• 2.2.5
• 2.2.6
• 2.2.7
• 2.2.8
• 2.2.9
• 2.2.10
• 2.2.11
• 2.2.12

CPE 2.3info

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CPE 2.2info

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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