CVE-2021-48012 fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML
Attackers can pollute Object.prototype via crafted TOML keys, leading to denial of service or authorization bypass in applications using fast-toml.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-48012?
CVE-2021-48012 is a high-severity vulnerability in Gin-Quin fast-toml, published on 12 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-1321
Which versions are affected by CVE-2021-48012?
How do I fix CVE-2021-48012?
No fix has been published for CVE-2021-48012 yet. Limit exposure of the affected software until one is available.
Is CVE-2021-48012 being exploited?
There is no known exploitation of CVE-2021-48012 in the wild and no public exploit code.
Sources
Also known as GHSA-qqfj-vf92-g76j.