CVE-2020-8127Public exploitNetwork attack vector

DOM script execution via unrestricted postMessage methods

Published Feb 28, 2020 · Updated Aug 4, 2024

DOM-based cross-site scripting in reveal.js 3.9.1 and earlier allows remote attackers to execute script via cross-origin messages. The postMessage handler accepts a caller-supplied Reveal method name and invokes addKeyBinding, which stores an unescaped description that showHelp renders as HTML. Exploitation requires user interaction with an attacker-controlled page and a presentation running with the default postMessage interface enabled.

CVSS severity6.1
Medium
EPSS probability1.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

DOM-based cross-site scripting in reveal.js 3.9.1 and earlier allows remote attackers to execute script via cross-origin messages. The postMessage handler accepts a caller-supplied Reveal method name and invokes addKeyBinding, which stores an unescaped description that showHelp renders as HTML. Exploitation requires user interaction with an attacker-controlled page and a presentation running with the default postMessage interface enabled.

The record

CVE
CVE-2020-8127
Published
Feb 28, 2020
Updated
Aug 4, 2024
Vendor
Hakim El Hattab
Product
reveal.js
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 28, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed version: 3.9.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hakim El Hattab · reveal.jsversion=Fixed version: 3.9.2

Published CVSS scores

6.1GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/A:N
6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo