CVE-2021-48012

fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML

Published Oct 12, 2026 CVSS 4.0 · 8.8 High EPSS < 1% KEV · Not listed
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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

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

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

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Oct 26, 2026, 5:37 PM
Reserved
Oct 12, 2026, 7:37 PM
Status
Deferred
Published
Oct 12, 2026, 9:17 PM
Modified
Oct 26, 2026, 6:17 PM