RHSA-2026:96076 - Security Advisory

Topic

An update for osbuild-composer is now available for Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support and Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On.

Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available for each vulnerability from the CVE link(s) in the References section.

Description

An image building service based on osbuild It is inspired by lorax-composer and exposes the same API. As such, it is a drop-in replacement.

Security Fix(es):

• crypto/tls: crypto/tls: Incorrect certificate validation during TLS session resumption (CVE-2025-68121)
• crypto/x509: golang: Go crypto/x509: Denial of Service via inefficient certificate chain validation (CVE-2026-32281)
• crypto/x509: golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application (CVE-2026-33810)
• crypto/x509: crypto/tls: golang: Go: Denial of Service vulnerability in certificate chain building (CVE-2026-32280)
• 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)
• github.com/labstack/echo: Echo: Unauthorized Information Disclosure via URL Path Decoding Discrepancy (CVE-2026-55677)
• 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)
• net/http: golang: golang: Denial of Service via crafted HTTP Range headers (CVE-2026-78667)
• crypto/tls: golang: crypto/tls: Denial of Service via multiple ECH outer extension references (CVE-2026-97031)
• net/textproto: mime/multipart: golang: golang: Denial of Service via memory limit bypass in multipart form parsing (CVE-2026-94440)
• net/http: net/http/internal/http2: golang.org/x/net/http2: net/http: Denial of Service via excessive HTTP/2 SETTINGS frames (CVE-2026-78669)

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.

Solution

For details on how to apply this update, which includes the changes described in this advisory, refer to:

https://access.redhat.com/articles/11258

Affected Products

• Red Hat Enterprise Linux for x86_64 - Extended Life Cycle Long Life 8.4 x86_64
• Red Hat Enterprise Linux Server - AUS 8.4 x86_64

Fixes

• BZ - 2437111 - CVE-2025-68121 crypto/tls: crypto/tls: Incorrect certificate validation during TLS session resumption
• BZ - 2456333 - CVE-2026-32281 crypto/x509: golang: Go crypto/x509: Denial of Service via inefficient certificate chain validation
• BZ - 2456335 - CVE-2026-33810 crypto/x509: golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application
• BZ - 2456339 - CVE-2026-32280 crypto/x509: crypto/tls: golang: Go: Denial of Service vulnerability in certificate chain building
• BZ - 2480756 - CVE-2026-39821 golang.org/x/net/idna: golang: net/http: golang.org/x/net/idna: Privilege escalation via incorrect Punycode label processing
• BZ - 2484204 - CVE-2026-42504 mime: golang: Golang MIME: Denial of Service via maliciously-crafted MIME header
• BZ - 2493622 - CVE-2026-55677 github.com/labstack/echo: Echo: Unauthorized Information Disclosure via URL Path Decoding Discrepancy
• BZ - 2515815 - CVE-2026-33818 encoding/asn1: golang: Go encoding/asn1: Denial of Service via excessive recursion in Unmarshal
• BZ - 2515820 - CVE-2026-56860 net/url: golang: golang net/url: Denial of Service from quadratic complexity in path resolution
• BZ - 2515827 - CVE-2026-56853 net/http: golang: Go net/http: Unencrypted HTTP/2 connections vulnerable to Denial of Service
• BZ - 2515838 - CVE-2026-56858 html/template: golang: Go html/template: Cross-Site Scripting via pathological input
• BZ - 2515839 - CVE-2026-56862 crypto/tls: golang: Golang crypto/tls: Denial of Service via indefinite KeyUpdate messages
• BZ - 2515840 - CVE-2026-56859 encoding/xml: golang: Go: Denial of Service via XML decoding recursion depth issue
• BZ - 2548334 - CVE-2026-78667 net/http: golang: golang: Denial of Service via crafted HTTP Range headers
• BZ - 2548336 - CVE-2026-97031 crypto/tls: golang: crypto/tls: Denial of Service via multiple ECH outer extension references
• BZ - 2548341 - CVE-2026-94440 net/textproto: mime/multipart: golang: golang: Denial of Service via memory limit bypass in multipart form parsing
• BZ - 2548344 - CVE-2026-78669 net/http: net/http/internal/http2: golang.org/x/net/http2: net/http: Denial of Service via excessive HTTP/2 SETTINGS frames

CVEs

• CVE-2025-68121
• CVE-2026-32280
• CVE-2026-32281
• CVE-2026-33810
• CVE-2026-33818
• CVE-2026-39821
• CVE-2026-42504
• CVE-2026-55677
• CVE-2026-56853
• CVE-2026-56858
• CVE-2026-56859
• CVE-2026-56860
• CVE-2026-56862
• CVE-2026-78667
• CVE-2026-78669
• CVE-2026-94440
• CVE-2026-97031

References

• https://access.redhat.com/security/updates/classification/#important