CVE-2022-32149: Denial of service via crafted Accept-Language header in golang.org/x/text/language

A vulnerability was found in the golang.org/x/text/language package. An attacker can craft an Accept-Language header which ParseAcceptLanguage will take significant time to parse. This issue leads to a denial of service, and can impact availability.

An attacker may cause a denial of service by crafting an Accept-Language header which ParseAcceptLanguage will take significant time to parse.

Denial of service via crafted Accept-Language header in golang.org/x/text/language

— Microsoft

Golang Go is vulnerable to a denial of service, caused by improper input validation by the golang.org/x/text/language package. By sending a specially-crafted Accept-Language header, a remote attacker could exploit this vulnerability to cause ParseAcceptLanguage to take significant time to parse, and results in a denial of service condition.

— IBM

The BCP 47 tag parser has quadratic time complexity due to inherent aspects of its design. Since the parser is, by design, exposed to untrusted user input, this can be leveraged to force a program to consume significant time parsing Accept-Language headers. The parser cannot be easily rewritten to fix this behavior for various reasons. Instead the solution implemented in this CL is to limit the total complexity of tags passed into ParseAcceptLanguage by limiting the number of dashes in the string to 1000. This should be more than enough for the majority of real world use cases, where the number of tags being sent is likely to be in the single digits.

Specific Go Packages Affected golang.org/x/text/language

— GitHub