Medium [CVE-2026-59710] Stored Cross-Site Scripting via unescaped table header ID attributes in markdown
This medium-severity Red Hat Linux advisory covers CVE-2026-59710 affecting Cryostat 4, Multicluster Engine for Kubernetes, Node HealthCheck Operator.
Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.
VulniPulse record published Record updated
Summary
showdown contains a stored cross-site scripting vulnerability in the parseHeaders function of src/subParsers/makehtml/tables.js that fails to properly escape table header ID attributes.
Attackers can inject arbitrary HTML and script-executing SVG elements through double-quote characters in markdown table headers, achieving stored XSS when untrusted markdown is rendered with the default github flavor configuration. A flaw was found in Showdown.
This vulnerability, a stored cross-site scripting (XSS) issue, allows an attacker to inject malicious code into web pages. When untrusted markdown is processed, this can lead to the execution of malicious scripts in a user's web browser, potentially compromising user data or session integrity.
Showdown, as integrated into Red Hat products, is susceptible to a stored cross-site scripting vulnerability. Affected versions: <= 2.1.0.
Red Hat severity: Moderate — CVSS 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N). Weakness: CWE-79.
Affected Red Hat products: Cryostat 4; Multicluster Engine for Kubernetes; Node HealthCheck Operator; Red Hat 3scale API Management Platform 2; Red Hat Advanced Cluster Management for Kubernetes 2; Red Hat Ansible Automation Platform 2; Red Hat OpenShift AI (RHOAI); Red Hat OpenShift Container Platform 4; Red Hat OpenShift Virtualization 4; Red Hat Quay 3.
Is CVE-2026-59710 exploited?
No exploitation is reported in the sources VulniPulse tracks: CVE-2026-59710 is not in the CISA KEV catalog (checked ) and this advisory does not report exploitation. That is not proof the vulnerability cannot be exploited.
How do I fix CVE-2026-59710?
The advisory VulniPulse tracks names no fixed release. Follow Red Hat's guidance for workarounds and updates.
Confirm against the vendor advisory before you patch.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
Mitigation checklist
- To mitigate this vulnerability, avoid rendering untrusted markdown content within applications utilizing Showdown. If processing untrusted markdown is unavoidable, ensure that all input is thoroughly sanitized before rendering to prevent the injection of malicious HTML or script-executing elements.
Official advisory · high-confidence parse· fetched 13 days ago·verify at source
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