Panic on inputs with large exponents in math/big

HIGH 7.5CVE-2021-33198 · BIT-golang-2021-33198 · GO-2021-0242 · Published 02/08/2021 · updated 17/06/2026

In short

CVE-2021-33198 is a HIGH (CVSS 7.5) vulnerability affecting stdlib, go (golang).
Chance of exploitation in the next 30 days (EPSS): 3.4%, higher than 88.8% of all vulnerabilities.
Fix: update to 1.16.5, 1.15.13 or later.

Package	Affected versions	Patched versions
stdlib Go	`≥ 1.16.0-0, < 1.16.5< 1.15.13`	`1.16.51.15.13`
go golang	`≥ 1.16.0, < 1.16.5< 1.15.13`	`1.16.51.15.13`

Rat.SetString and Rat.UnmarshalText may cause a panic or an unrecoverable fatal error if passed inputs with very large exponents.

NVD description

In Go before 1.15.13 and 1.16.x before 1.16.5, there can be a panic for a large exponent to the math/big.Rat SetString or UnmarshalText method.

Running one of these products? Scan your site to see whether it exposes a vulnerable version.

Package

Affected versions

Patched versions

≥ 1.16.0-0, < 1.16.5< 1.15.13

1.16.51.15.13

≥ 1.16.0, < 1.16.5< 1.15.13

1.16.51.15.13

More vulnerabilities in stdlib

See all →