Red Hat Security Advisory: golang security, bug fix, and enhancement update

Fixed packages 8

Vulnerabilities 3

• High 7.5
  CVE-2026-42504

  Quadratic complexity in WordDecoder.DecodeHeader in mime

  Decoding a maliciously-crafted MIME header containing many invalid encoded-words can consume excessive CPU.

  Go standard library mime golang go Debian Ubuntu Azure Linux Alpine Wolfi Go
  Jun 2, 2026
• Medium 6.5
  CVE-2026-27145 Public exploit

  Inefficient candidate hostname parsing in crypto/x509

  (*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 c…

  Go standard library crypto/x509 golang stdlib Debian Ubuntu Azure Linux Wolfi Go
  Jun 2, 2026
• Medium 5.3
  CVE-2026-42507

  Arbitrary inputs are included in errors without any escaping in net/textproto

  When returning errors, functions in the net/textproto package would include its input as part of the error. This might allow an attacker to inject misleading content to errors that are printed or logged.

  Go standard library net/textproto golang go Debian Ubuntu Azure Linux Alpine Wolfi Go
  Jun 2, 2026

References

• article
  https://access.redhat.com/security/updates/classification/#moderate
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2484205
• article
  https://issues.redhat.com/browse/RHEL-183347
• advisory
  https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_29980.json
• report
  https://access.redhat.com/security/cve/CVE-2026-27145
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2484207
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-27145
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-27145
• article
  https://go.dev/cl/783621
• article
  https://go.dev/issue/79694
• article
  https://groups.google.com/g/golang-announce/c/tKs3rmcBcKw
• advisory
  https://pkg.go.dev/vuln/GO-2026-5037
• report
  https://access.redhat.com/security/cve/CVE-2026-42504
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2484204
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-42504
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-42504
• article
  https://go.dev/cl/774481
• article
  https://go.dev/issue/79217
• advisory
  https://pkg.go.dev/vuln/GO-2026-5038
• report
  https://access.redhat.com/security/cve/CVE-2026-42507
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-42507
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-42507
• article
  https://go.dev/cl/777060
• article
  https://go.dev/issue/79346
• advisory
  https://pkg.go.dev/vuln/GO-2026-5039