golang.org/x/text/language in golang.org/x/text before 0.3.7 can panic with an out-of-bounds read during BCP 47 language tag parsing. Index calculation is mishandled. If parsing untrusted user input, this can be used as a vector for a denial-of-service attack.

References

• https://nvd.nist.gov/vuln/detail/CVE-2021-38561
• https://deps.dev/advisory/OSV/GO-2021-0113
• https://go.googlesource.com/text/+/383b2e75a7a4198c42f8f87833eefb772868a56f
• https://groups.google.com/g/golang-announce
• https://pkg.go.dev/golang.org/x/text/language
• https://go.dev/cl/340830
• https://pkg.go.dev/vuln/GO-2021-0113