Description
The ToASCII and ToUnicode functions incorrectly accept Punycode-encoded labels that decode to an ASCII-only label. For example, ToUnicode("xn--example-.com") incorrectly returns the name "example.com" rather than an error. This behavior can lead to privilege escalation in programs using the idna package. For example, a program which performs privilege checks on the ASCII hostname may reject "example.com" but permit "xn--example-.com". If that program subsequently converts the ASCII hostname to Unicode, it will inadvertently permits access to the Unicode name "example.com".
Problem types
CWE-1289: Improper Validation of Unsafe Equivalence in Input
Product status
Any version before 0.55.0
Credits
KC1zs4 (https://github.com/KC1zs4)
References
groups.google.com/g/golang-announce/c/iI-mYSI0lu8