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.
Published: 2026-10-12
Score: 8.8 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories

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History

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'}

Subscriptions

No data.

cve-icon MITRE

Status: PUBLISHED

Assigner: VulnCheck

Published:

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

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

Link: CVE-2021-48012

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

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

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

Link: CVE-2021-48012

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-12T22:30:07Z

Weaknesses