CVE-2021-48012
fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- High
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
fast-toml through 0.5.4 Prototype Pollution via __proto__ Keys in Parsed TOML
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.
- Record
CVE-2021-48012- CVSS 4.0
- 8.8 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L - Weakness
- CWE-1321
- Updated
- 2026-11-02
EUVDEUVD-2021-34885
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.
- Record
EUVD-2021-34885- CVSS 4.0
- 8.8 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-qqfj-vf92-g76j
fast-toml through 0.5.4 contains a prototype pollution vulnerability that allows attackers to...
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.
- Record
GHSA-qqfj-vf92-g76j- CVSS 4.0
- 8.8 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L - Weakness
- CWE-1321
- Updated
- 2026-11-02
NVD
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.
- Record
CVE-2021-48012- CVSS 4.0
- 8.8 High
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - CVSS 3.1
- 8.2 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L - Weakness
- CWE-1321
- Updated
- 2026-11-02
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-48012 is a high vulnerability (CVSS 8.8) in Gin-quin Fast-toml, published October 12, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.41%, the 36th percentile. No source names a fixed version.