high · 8.2

fast-toml through 0.5.4 contains a prototype pollution vulnerability that allows attackers to modify Object.prototype by supplying TOML c…

CVE-2021-48012 · published 12 Oct 2026

How serious is it

  • Severity: high, CVSS score 8.2 out of 10.
  • No exploit prediction (EPSS) score yet.
  • Not on the CISA list of exploited vulnerabilities.
  • No public exploit in Exploit-DB.

Is your app affected by CVE-2021-48012?

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Who is affected

  • Gin-Quin fast-toml: <= 0.5.4

How to check

  1. Find out whether you run the affected product and which version, then compare it with the versions above.

How to fix

Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
  1. Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
  2. If a vulnerable version was live, check your logs and rotate the secrets that server could read.

The advisory

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.

Check your whole app

Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.

References

Merged from NVD. Last updated 25 Oct 2026. All vulnerabilities · RSS · JSON

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