CVE-2021-48012fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML
Updated under an hour ago ()
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It affects Gin-Quin fast-toml. Add what you run to find out whether that includes you.
EPSS puts the chance of exploitation in the next 30 days at 0.41%, higher than 34% of scored CVEs.
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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.
- CVSS
- 8.2 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
- Weakness (CWE)
- CWE-1321
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- 0.41% (percentile 34)
- Assigned by
- VulnCheck
- NVD analysis
- Deferred
- Record last updated
- Oct 12, 2026
- First seen by InfoSec Signals
- Oct 12, 2026
Affected products
Gin-Quin fast-toml gin_quin:fast_toml (from the name) | through 0.5.4 | CNA record |
References
- https://github.com/Gin-Quin/fast-toml/issues/8issue-tracking
- https://github.com/Gin-Quin/fast-toml/pull/3issue-tracking, patch
- https://github.com/Gin-Quin/fast-tomlproduct
- https://www.vulncheck.com/advisories/fast-toml-through-0.5.4-prototype-pollution-via-proto-keys-in-parsed-tomlthird-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.