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CVE-2021-48012high8.8

fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML

Impact

fast-toml versions 0.5.4 and below contain a prototype pollution vulnerability, allowing attackers to modify Object.prototype with crafted TOML input, potentially causing denial of service or authorization bypass. Attackers must supply specific key segments to parse().

Summarized by @cf/meta/llama-3.3-70b-instruct-fp8-fast. Verify details against the original sources.

Affected packages

This source has no supported package-version data for matching. You can read the advisory here, but this record alone cannot power a dependency check.

Affected products

Vendor version evidence. Product records are separate from automatic dependency matching.

Gin-Quin · VulnCheck

fast-toml

1 range
VulnCheck version evidence

Package identity

pkg:npm/fast-tomlExplore fast-toml →

Identity supplied by VulnCheck. Version matching requires compatible range evidence.

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affected

0 → through 0.5.4

semver versions

unaffected

unknown

Other versions: unaffected

Original source 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.

Inside the record

Evidence available

Package identity
Version evidence
Remediation guidance · not supplied
Weakness classification
Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2021-48012

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-1321 ↗

Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

VulnCheck

Related →
Contributing organizations · 2
VulnCheck

Assigning organization

2026-10-12
CISA-ADP

Additional data publisher

2026-10-26

What changed

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References

4 sources
github.com/Gin-Quin/fast-toml/pull/3
issue-trackingVulnCheck
github.com/Gin-Quin/fast-toml/issues/8
issue-trackingVulnCheck
github.com/Gin-Quin/fast-toml
productVulnCheck
www.vulncheck.com/advisories/fast-toml-through-0.5.4-prototype-pollution-via-proto-keys-in-parsed-toml
third-party-advisoryVulnCheck