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Fencer Vulns
high 7.2

CVE-2021-47839 json

Marky 0.0.1 - Persistent Cross-Site Scripting

published 2026-01-16 9 mo ago modified 2026-07-15 3 mo ago also EUVD-2026-2874

cvss
7.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 40%
public exploits
0
none known

Summary

Marky 0.0.1 contains a persistent cross-site scripting vulnerability that allows attackers to inject malicious scripts into markdown files. Attackers can upload crafted markdown files with embedded JavaScript payloads that execute when the file is opened, potentially enabling remote code execution.

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-2021-47839 updated

marky: Marky: Remote Code Execution via persistent cross-site scripting

  • Red Hat Logging Subsystem for Red Hat OpenShift openshift-logging/vector-rhel9, openshift-logging/fluentd-rhel9, openshift-logging/eventrouter-rhel9, openshift-logging/logging-view-plugin-rhel9, openshift-logging/cluster-logging-rhel9-operator, openshift-logging/log-file-metric-exporter-rhel9, +1 more Red Hat Satellite 6 satellite/iop-vulnerability-frontend-rhel9
    not affected: vulnerable code not present

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
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
9 mo ago

Exploit prediction

0.46% chance of exploitation in the next 30 days, higher than 40% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • exploit-db.com https://www.exploit-db.com/exploits/49831 referenced PoC, tagged "exploit" by a source, unverified
  • imgur.com https://imgur.com/a/qclfrUx referenced PoC, tagged "exploit" by a source, unverified
  • vulncheck.com https://www.vulncheck.com/advisories/marky-persistent-cross-site-scripting referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N
CNA 3.1 7.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
CNA 4.0 5.1 CVSS:4.0/AV:N/AC:L/AT:N/PR:L/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

  • vesparny Marky
  • Red Hat Logging Subsystem for Red Hat OpenShift
  • Red Hat Red Hat Satellite 6

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.