RHSA-2026:53374HighCVSS 8.2

Red Hat Security Advisory: rhc security update

Published
August 11, 2026
Last Modified
August 11, 2026

🔗 CVE IDs covered (2)

CVE-2026-27145 →CVE-2026-39821 →

📋 Description

CVE-2026-27145 — crypto/x509: golang: golang crypto/x509: Denial of Service via excessive processing of DNS SAN entries CVE-2026-39821 — golang.org/x/net/idna: golang: net/http: golang.org/x/net/idna: Privilege escalation via incorrect Punycode label processing

🎯 Affected products14

  • Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-1:0.3.2-5.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-1:0.3.2-5.el10_0.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-1:0.3.2-5.el10_0.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-1:0.3.2-5.el10_0.src as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-1:0.3.2-5.el10_0.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-debuginfo-1:0.3.2-5.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-debuginfo-1:0.3.2-5.el10_0.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-debuginfo-1:0.3.2-5.el10_0.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-debuginfo-1:0.3.2-5.el10_0.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-debugsource-1:0.3.2-5.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-debugsource-1:0.3.2-5.el10_0.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-debugsource-1:0.3.2-5.el10_0.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • rhc-debugsource-1:0.3.2-5.el10_0.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)

✅ Remediation

For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Workaround: A flaw was found in the Go standard library crypto/x509 package. When verifying a TLS certificate hostname, VerifyHostname processed each DNS Subject Alternative Name (SAN) entry in a loop and repeatedly split the candidate hostname on "." characters. For certificates with a very large DNS SAN list, CPU use could grow quadratically with the number of SAN entries and hostname labels. Because hostname verification runs before the certificate chain is built, this overhead can occur even when the certificate is not trusted. Red Hat rates this issue as Important. It affects Red Hat products that include the Go standard library crypto/x509 code from an affected Go toolchain version (before Go 1.25.11, or from Go 1.26.0 through Go 1.26.3). Applications and container images built with a fixed Go release (1.25.11 or later, or 1.26.4 or later) are not affected. Community distributions such as Fedora are also affected. Upstream fix: Go 1.25.11 and Go 1.26.4 (GO-2026-5037). Workaround: Upgrade to a fixed golang.org/x/net release that includes the idna correction, via updated golang or dependent package rebuilds.

🔗 References (5)