CVE-2025-55195: denoland std Prototype Pollution

Vulnerability summary

CVE-2025-55195 is a high (CVSS 7.3) Prototype Pollution vulnerability in denoland std. EPSS estimates a 0.34% chance of exploitation in the next 30 days, higher than 26.3% of scored vulnerabilities.

Timeline

1. 14-08-2025
   PublishedVulnerability first disclosed.
2. 14-08-2025
   Last modifiedVulnerability information updated.

Description

@std/toml is the Deno Standard Library. Prior to version 1.0.9, an attacker can pollute the prototype chain in Node.js runtime and Browser when parsing untrusted TOML data, thus achieving Prototype Pollution (PP) vulnerability. This is because the library is merging an untrusted object with an empty object, which by default the empty object has the prototype chain. This issue has been patched in version 1.0.9.

• CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.