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Fencer Vulns
medium 6.1

CVE-2026-104477 json

Showdown through 2.1.0 XSS via unescaped quote in href and src attributes

published 2026-10-02 37 d ago modified 2026-10-06 33 d ago also EUVD-2026-91853

cvss
6.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 8%
public exploits
0
none known

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.

Patch / fix

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-104477 updated cvss 6.1

showdown: showdown: Cross-site scripting via unescaped double quotes in link and image attributes

  • Red Hat Cryostat 4 cryostat/cryostat-openshift-console-plugin-rhel9
    affected: no fix available “Fix deferred”
  • Red Hat Multicluster Engine for Kubernetes multicluster-engine/console-mce-rhel9 Red Hat Node HealthCheck Operator workload-availability/node-remediation-console-rhel8, workload-availability/node-healthcheck-rhel9-operator, workload-availability/node-healthcheck-operator-bundle, workload-availability/node-healthcheck-must-gather-rhel9 Red Hat 3scale API Management Platform 2 3scale-amp2/system-rhel8 Red Hat Advanced Cluster Management for Kubernetes 2 rhacm2/console-rhel9 Red Hat Ansible Automation Platform 2 automation-gateway 2.5.20260923-1.el9ap, automation-eda-controller 1.0.10-0.1.20260317.git9cae940.el8ap
    affected: no fix planned “Out of support scope”
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-mlflow-rhel9, rhoai/odh-core-bff-rhel9, rhoai/odh-dashboard-rhel9, rhoai/odh-mod-arch-maas-rhel9, rhoai/odh-mod-arch-automl-rhel9, rhoai/odh-mod-arch-gen-ai-rhel9, +6 more Red Hat OpenShift Container Platform 4 openshift4/ose-console, openshift4/ose-console-rhel9, openshift4/ose-monitoring-plugin-rhel8
    affected: no fix available “Fix deferred”
  • Red Hat OpenShift Virtualization 4 container-native-virtualization/kubevirt-console-plugin-rhel9, openshift-virtualization/konflux-builds/v4-12/kubevirt-console-plugin, openshift-virtualization/konflux-builds/v4-22/kubevirt-console-plugin-rhel9 Red Hat Quay 3 quay/quay-rhel8, quay/quay-rhel9
    affected: no fix available, no fix planned “Out of support scope”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
34 d ago

Exploit prediction

0.19% chance of exploitation in the next 30 days, higher than 8% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
CNA 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CNA 4.0 5.3 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

  • showdownjs showdown

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.