CVE-2021-48012
fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML
- State
- Published
- Severity
- 8.8 High
- Published
- Oct 12, 2026
- Updated
- Oct 26, 2026
- Reserved
- Oct 12, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.8 High | 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 | VulnCheck |
| 3.1 | 8.2 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L | VulnCheck |
Weaknesses
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Products
| Product | Versions |
|---|---|
fast-tomlGin-Quin |
|
References
- GitHub Issue #8issue-tracking
- GitHub Pull Request #3issue-trackingpatch
- https://github.com/Gin-Quin/fast-tomlproduct
- VulnCheck Advisory: fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOMLthird-party-advisory
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