[security] Go 1.26.4 and Go 1.25.11 are released

[anno...@golang.org]

Hello gophers,

We have just released Go versions 1.26.4 and 1.25.11, minor point releases.

These releases include 3 security fixes following the security policy:

• mime: quadratic complexity in WordDecoder.DecodeHeader

  Decoding a maliciously-crafted MIME header containing many invalid
  encoded-words could consume excessive CPU.
  The MIME decoder now better handles this case.

  Thanks to p4p3r (https://hackerone.com/p4p3r_hak) for reporting this issue.

  This is CVE-2026-42504 and Go issue https://go.dev/issue/79217.

• net/textproto: arbitrary input are included in errors without any escaping

  When returning errors, functions in the net/textproto package would
  include its input as part of the error, without any escaping. Note that
  said input is often controlled by external parties when using this
  package naturally. For example, a net/http client uses ReadMIMEHeader
  when parsing the headers it receive from a server.

  As a result, an attacker could inject arbitrary content into the error.
  Practically, this can result in an attacker injecting misleading
  content, terminal control bytes, etc. into a victim's output or logs.

  This is CVE-2026-42507 and Go issue https://go.dev/issue/79346

• crypto/x509: split candidate hostname only once

  (*x509.Certificate).VerifyHostname previously called matchHostnames in a loop
  over all DNS Subject Alternative Name (SAN) entries. This caused
  strings.Split(host, ".") to execute repeatedly on the same input hostname.

  With a large DNS SAN list, verification costs scaled quadratically based on the
  number of SAN entries multiplied by the hostname's label count. Because
  x509.Verify validates hostnames before building the certificate chain, this
  overhead occurred even for untrusted certificates.

  Thanks to Jakub Ciolek (https://ciolek.dev) for reporting this issue.

  This is CVE-2026-27145 and https://go.dev/issue/79694.

View the release notes for more information:
https://go.dev/doc/devel/release#go1.26.4

You can download binary and source distributions from the Go website:
https://go.dev/dl/

To compile from source using a Git clone, update to the release with
git checkout go1.26.4 and build as usual.

Thanks to everyone who contributed to the releases.

Cheers,
The Go team