RHSA-2026:61253: Important: golang security update
The golang packages provide the Go programming language compiler.Security Fix(es): crypto/x509: Incorrect enforcement of email constraints in crypto/x509 (CVE-2026-27137) crypto/x509: golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application (CVE-2026-33810) net/mail: golang: net/mail: Denial of Service via pathological email address parsing (CVE-2026-42499) cmd/go: golang: Go command (cmd/go): Integrity bypass due to checksum validation flaw via malicious module proxy (CVE-2026-42501) html/template: golang: Go html/template: Cross-Site Scripting via improper URL escaping in meta tag content (CVE-2026-39823) cmd/go: golang: Go 'go bug' command: Arbitrary file overwrite via symlink attack (CVE-2026-39819) net/http/internal/http2: golang: golang.org/x/net: Go HTTP/2: Denial of Service via malformed SETTINGSMAXFRAMESIZE frame (CVE-2026-33814) net/mail: golang: Go net/mail: Denial of Service via crafted email inputs (CVE-2026-39820) net: golang: Go net package: Denial of Service via long CNAME response in LookupCNAME (CVE-2026-33811) net/http/httputil: golang: net/http/httputil: ReverseProxy forwards hidden query parameters, potentially bypassing security controls (CVE-2026-39825) cmd/go: golang: Go tool pack: Arbitrary file write via malicious archive extraction (CVE-2026-39817) html/template: golang: html/template: Cross-site scripting due to incorrect script tag escaping (CVE-2026-39826) golang.org/x/net/idna: golang: net/http: golang.org/x/net/idna: Privilege escalation via incorrect Punycode label processing (CVE-2026-39821) net/textproto: golang: Golang net/textproto: Misleading error messages via input injection (CVE-2026-42507) crypto/x509: golang: golang crypto/x509: Denial of Service via excessive processing of DNS SAN entries (CVE-2026-27145) golang: Go os.Root: Symlink following vulnerability allows directory traversal (CVE-2026-39822) 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.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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redhat/golangto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2 - Upgrade
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redhat/go-toolsetto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2 - Upgrade
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redhat/golang-binto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2 - Upgrade
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redhat/golang-docsto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2 - Upgrade
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redhat/golang-miscto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2 - Upgrade
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redhat/golang-raceto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2 - Upgrade
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redhat/golang-srcto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2 - Upgrade
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redhat/golang-teststo a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2 - Upgrade
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redhat/go-toolsetto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2.aa - Upgrade
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redhat/golangto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2.aa - Upgrade
Upgrade
redhat/golang-binto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2.aa - Upgrade
Upgrade
redhat/golang-raceto a version that resolves this vulnerability.Fixed in 1.26.5-1.el9_2.aa
Event History
Frequently Asked Questions
Which installed packages should be reviewed for exposure?
Review systems using the listed Red Hat Go packages: golang, go-toolset, golang-bin, golang-race, golang-docs, golang-misc, golang-src, and golang-tests. Exposure depends on whether the installed Go toolchain or applications use the affected components, including crypto/x509, net/mail, cmd/go, html/template, net/http, and net.
What attacker-controlled inputs or conditions are implicated?
The issues include malicious certificates and DNS constraints, pathological or crafted email addresses, malformed HTTP/2 SETTINGS_MAX_FRAME_SIZE frames, long CNAME responses, malicious module proxies, and symlink attacks against the go bug command. One issue also involves URL content in HTML meta tags, and another concerns hidden query parameters forwarded by ReverseProxy.
Are these issues limited to Go developers and build systems?
No. Some findings affect Go command tooling, including module checksum validation and the go bug command, but others affect applications that validate certificates, parse email addresses, use HTTP/2, perform CNAME lookups, render HTML templates, or run reverse proxies.