RHSA-2026:67517HighCVSS 8.8

Red Hat Security Advisory: grafana security update

Published
September 15, 2026
Last Modified
September 19, 2026

🔗 CVE IDs covered (19)

CVE-2026-56859 →CVE-2026-33376 →CVE-2026-39821 →CVE-2026-42499 →CVE-2026-56858 →CVE-2026-56860 →CVE-2026-25681 →CVE-2026-42127 →CVE-2026-8609 →CVE-2026-33818 →CVE-2026-39820 →CVE-2026-42502 →CVE-2026-56853 →CVE-2026-56862 →CVE-2026-27136 →CVE-2026-27137 →CVE-2026-33377 →CVE-2026-33382 →CVE-2026-33810 →

📋 Description

CVE-2026-8609 — grafana: Grafana: Denial of Service via unbounded memory growth in OAuth login route CVE-2026-25681 — golang.org/x/net/html: golang.org/x/net/html: Arbitrary code execution via Cross-Site Scripting CVE-2026-27136 — golang.org/x/net/html: golang: golang.org/x/net/html: Cross-Site Scripting via HTML parsing bypass CVE-2026-27137 — crypto/x509: Incorrect enforcement of email constraints in crypto/x509 CVE-2026-33376 — grafana: Grafana Auth Proxy: Unauthorized access due to incorrect IPv6 allow-list default CVE-2026-33377 — grafana: Grafana: Privilege escalation via dashboard overwrite CVE-2026-33382 — grafana: Grafana: Denial of Service via excessive memory allocation from large API request payloads CVE-2026-33810 — crypto/x509: golang: Go crypto/x509: Certificate validation bypass due to incorrect DNS constraint application CVE-2026-33818 — encoding/asn1: golang: Go encoding/asn1: Denial of Service via excessive recursion in Unmarshal CVE-2026-39820 — net/mail: golang: Go net/mail: Denial of Service via crafted email inputs CVE-2026-39821 — golang.org/x/net/idna: golang: net/http: golang.org/x/net/idna: Privilege escalation via incorrect Punycode label processing CVE-2026-42127 — grafana: Grafana: Denial of Service due to excessive memory allocation via large JSON payloads CVE-2026-42499 — net/mail: golang: net/mail: Denial of Service via pathological email address parsing CVE-2026-42502 — golang.org/x/net/html: golang: golang.org/x/net/html: Cross-Site Scripting via unexpected HTML tree rendering CVE-2026-56853 — net/http: golang: Go net/http: Unencrypted HTTP/2 connections vulnerable to Denial of Service CVE-2026-56858 — html/template: golang: Go html/template: Cross-Site Scripting via pathological input CVE-2026-56859 — encoding/xml: golang: Go: Denial of Service via XML decoding recursion depth issue CVE-2026-56860 — net/url: golang: golang net/url: Denial of Service from quadratic complexity in path resolution CVE-2026-56862 — crypto/tls: golang: Golang crypto/tls: Denial of Service via indefinite KeyUpdate messages

🎯 Affected products18

  • Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-0:10.2.6-26.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-0:10.2.6-26.el10_0.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-0:10.2.6-26.el10_0.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-0:10.2.6-26.el10_0.src as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-0:10.2.6-26.el10_0.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-debuginfo-0:10.2.6-26.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-debuginfo-0:10.2.6-26.el10_0.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-debuginfo-0:10.2.6-26.el10_0.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-debuginfo-0:10.2.6-26.el10_0.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-debugsource-0:10.2.6-26.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-debugsource-0:10.2.6-26.el10_0.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-debugsource-0:10.2.6-26.el10_0.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-debugsource-0:10.2.6-26.el10_0.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-selinux-0:10.2.6-26.el10_0.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-selinux-0:10.2.6-26.el10_0.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-selinux-0:10.2.6-26.el10_0.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
  • grafana-selinux-0:10.2.6-26.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: To mitigate this issue, restrict network access to the Grafana instance to trusted internal networks or localhost. If a reverse proxy or load balancer is deployed in front of Grafana, configure it to implement rate limiting on requests to the OAuth login endpoint to prevent an attacker from exhausting system resources. If OAuth is not required, consider disabling it in the Grafana configuration, though this may impact user authentication workflows. Workaround: To mitigate this flaw, applications processing untrusted HTML input must implement strict input sanitization and ensure all output is properly encoded before rendering. Deploying a comprehensive Content Security Policy (CSP) can restrict script execution, further reducing the attack surface. Administrators should review application configurations to ensure adequate protection against XSS. Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability. Workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Workaround: To mitigate this issue, explicitly specify the intended IPv6 address mask—typically /128 for a single host—within the Grafana Auth Proxy allow-list configuration. This overrides the incorrect default /32 mask, ensuring that network access restrictions are applied strictly as intended. For RHEL: Update the whitelist directive under the [auth.proxy] section in /etc/grafana/grafana.ini. For example, if ::1 is the desired address, configure it explicitly as ::1/128. A restart of the Grafana service (systemctl restart grafana-server) is required for the changes to take effect. Workaround: Audit dashboard-level permissions to ensure that write access is granted only to users who should be able to modify each specific dashboard. Revoke per-dashboard write permissions from Editor users who do not strictly require them. Workaround: Deploy a reverse proxy or API gateway (e.g., Nginx) in front of Grafana configured to strictly limit the maximum HTTP request body size, dropping oversized payloads before they reach the backend. As a defense-in-depth measure, restrict network access to trusted internal clients via firewall rules. Note: Applying these proxy and network changes may require a service reload, causing a temporary interruption. Workaround: Upgrade to a fixed golang.org/x/net release that includes the idna correction, via updated golang or dependent package rebuilds. Workaround: Restrict network access to the Grafana instance to only trusted clients and networks. This can be achieved by configuring firewall rules to limit inbound connections to the Grafana service port. If Grafana is exposed via a reverse proxy, ensure the proxy is configured to limit request body sizes to prevent large payloads from reaching Grafana. A service restart may be required for network configuration changes to take effect. Workaround: Applications utilizing `golang.org/x/net/html` should implement robust sanitization of all untrusted HTML input before rendering to prevent the creation of unexpected HTML structures that could facilitate XSS attacks. If an application does not require rendering arbitrary HTML, it should avoid processing such input.

🔗 References (22)