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GO-2026-4947

Unexpected work during chain building in crypto/x509

Quick fix

GO-2026-4947 — stdlib: upgrade to the fixed version with the command below.

go get stdlib@v1.25.9

Details

During chain building, the amount of work that is done is not correctly limited when a large number of intermediate certificates are passed in VerifyOptions.Intermediates, which can lead to a denial of service. This affects both direct users of crypto/x509 and users of crypto/tls.

Are you affected?

Enter the version of the package you're using.

Affected packages

Go/stdlib

Introduced in: 0Fixed in: 1.25.9

Fixgo get stdlib@v1.25.9

References

https://go.dev/cl/758320[FIX]
https://go.dev/issue/78282[REPORT]
https://groups.google.com/g/golang-announce/c/0uYbvbPZRWU[WEB]