Showdown through 2.1.0 XSS via unescaped quote in href and src attributes
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- Deferred Red Hat: fix deferred
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-79.
Summary
Showdown through 2.1.0 contains a cross-site scripting vulnerability in the makehtml link and image subparsers, which fail to escape double quotes in destination URLs placed into href and src attributes. Attackers can craft markdown links or images containing a double quote followed by onerror or onmouseover handlers to execute script when victims view rendered HTML.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Showdownjs | showdown | up to 2.1.0 | — | No fix listed | CNA |
- showdown VendorShowdownjs Affected up to 2.1.0 Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Cryostat 4 | Affected | No fix yet: Fix deferred |
| Multicluster Engine for Kubernetes | Affected | No fix planned: Out of support scope |
| Node HealthCheck Operator | Affected | No fix planned: Out of support scope |
| Red Hat 3scale API Management Platform 2 | Affected | No fix planned: Out of support scope |
| Red Hat Advanced Cluster Management for Kubernetes 2 | Affected | No fix planned: Out of support scope |
| Red Hat Ansible Automation Platform 2 | Affected | No fix planned: Out of support scope |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Container Platform 4 | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Virtualization 4 | Affected | No fix yet: Fix deferred |
| Red Hat Quay 3 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-03 Threatist record created from CVE-2026-104477
- 2026-10-03 Alias added: GHSA-gc85-xrjc-cv75
- 2026-10-06 CISA SSVC decision points changed
- 2026-10-06 Affected versions changed · Red Hat
References
Patch 1
More Showdownjs vulnerabilities
- TI-2024-01768 Showdownjs Denial of Service CVSS 3.1MEDIUM 5.3
Sources
- CVE-2026-104477 · CVE Program
- CVE-2026-104477 · NVD
- FIRST EPSS
- GHSA-gc85-xrjc-cv75 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-104477 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences