Issued at: 2026-09-09
Updated at: 2026-09-10
Advisory content derived from Red Hat RHSA-2026:65153, © Red Hat, Inc., used under CC BY 4.0, with modifications.
Synopsis
Important: osbuild-composer security update
Description
A service for building customized OS artifacts, such as VM images and OSTree commits, that uses osbuild under the hood. Besides building images for local usage, it can also upload images directly to cloud. It is compatible with composer-cli and cockpit-composer clients.
Security Fix(es):
* net/mail: golang: net/mail: Denial of Service via pathological email address parsing (CVE-2026-42499)
* net/mail: golang: Go net/mail: Denial of Service via crafted email inputs (CVE-2026-39820)
* golang.org/x/net/idna: golang: net/http: golang.org/x/net/idna: Privilege escalation via incorrect Punycode label processing (CVE-2026-39821)
* mime: golang: Golang MIME: Denial of Service via maliciously-crafted MIME header (CVE-2026-42504)
* encoding/asn1: golang: Go encoding/asn1: Denial of Service via excessive recursion in Unmarshal (CVE-2026-33818)
* net/url: golang: golang net/url: Denial of Service from quadratic complexity in path resolution (CVE-2026-56860)
* net/http: golang: Go net/http: Unencrypted HTTP/2 connections vulnerable to Denial of Service (CVE-2026-56853)
* html/template: golang: Go html/template: Cross-Site Scripting via pathological input (CVE-2026-56858)
* crypto/tls: golang: Golang crypto/tls: Denial of Service via indefinite KeyUpdate messages (CVE-2026-56862)
* encoding/xml: golang: Go: Denial of Service via XML decoding recursion depth issue (CVE-2026-56859)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.