fast-toml through 0.5.4 contains a prototype pollution vulnerability that allows attackers to modify Object.prototype by supplying TOML containing __proto__, constructor or prototype key segments. Attackers can pass [__proto__] or [constructor.prototype] table headers or __proto__.x dotted keys to parse() to pollute all objects, causing denial of service or authorization bypass.
History

Mon, 26 Oct 2026 18:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 13 Oct 2026 07:45:00 +0000

Type Values Removed Values Added
First Time appeared Gin-quin
Gin-quin fast-toml
Vendors & Products Gin-quin
Gin-quin fast-toml

Mon, 12 Oct 2026 21:00:00 +0000

Type Values Removed Values Added
Description fast-toml through 0.5.4 contains a prototype pollution vulnerability that allows attackers to modify Object.prototype by supplying TOML containing __proto__, constructor or prototype key segments. Attackers can pass [__proto__] or [constructor.prototype] table headers or __proto__.x dotted keys to parse() to pollute all objects, causing denial of service or authorization bypass.
Title fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML
Weaknesses CWE-1321
References
Metrics cvssV3_1

{'score': 8.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L'}

cvssV4_0

{'score': 8.8, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published: 2026-10-12T20:55:05.966Z

Updated: 2026-10-26T17:37:12.265Z

Reserved: 2026-10-12T19:37:38.614Z

Link: CVE-2021-48012

cve-icon Vulnrichment

Updated: 2026-10-26T17:36:18.162Z

cve-icon NVD

Status : Deferred

Published: 2026-10-12T21:17:06.057

Modified: 2026-10-26T18:17:04.217

Link: CVE-2021-48012

cve-icon Redhat

No data.