Prototype Pollution in Gin-Quin Fast-Toml
CVE-2021-48012
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.
Vulnerability class: Prototype Pollution
Published .
CVSS v3 metric
CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/Gin-Quin/fast-toml/issues/8 (issue-tracking)
- github.com/Gin-Quin/fast-toml/pull/3 (issue-tracking, patch)
- github.com/Gin-Quin/fast-toml (product)
- www.vulncheck.com/advisories/fast-toml-through-0.5.4-prototype-pollution-via-pr… (third-party-advisory)
Frequently asked questions
- What is CVE-2021-48012?
- CVE-2021-48012 is a high-severity vulnerability in Gin-Quin Fast-Toml, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 8.2/10. Published 2026-10-12.
- How severe is CVE-2021-48012?
- High severity. CVSS v3 base score is 8.2 out of 10.