High

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

Type: advisorySources: Official CVE List

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.

Products: fast-toml
Affected versions: Not specified
Fixed versions: Not specified
CVEs: CVE-2021-48012
Confirmed fixed CVEs: Not specified
Updated in this feed: 30 Oct 2026, 15:55 UTC · Revision 2

Source evidence

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

core-cve · Original source

Published 12 Oct 2026, 20:55 UTC

cve:CVE-2021-48012

fast-toml

Fixed versions: Not specified

Complete source record

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  "url": "https://www.cve.org/CVERecord?id=CVE-2021-48012",
  "method": "structured",
  "payload": {
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    "title": "fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML",
    "summary": "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.",
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}