CVE-2021-24378Public exploitNetwork attack vector

Stored XSS via unchecked imported HTML files

Published Jun 21, 2021 · Updated Aug 3, 2024

Stored XSS in Optimizing Matters Autoptimize before 2.7.8 allows remote authenticated users to execute JavaScript in a victim's browser. The Import Settings handler extracts attacker-supplied archives without rejecting .html entries, leaving a script-bearing index.html reachable in the plugin upload directory. Exploitation requires a high-privilege WordPress account to import the archive and a victim to open the extracted page, exposing that browser session to stored script execution.

CVSS severity4.8
Medium
EPSS probability0.62%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in Optimizing Matters Autoptimize before 2.7.8 allows remote authenticated users to execute JavaScript in a victim's browser. The Import Settings handler extracts attacker-supplied archives without rejecting .html entries, leaving a script-bearing index.html reachable in the plugin upload directory. Exploitation requires a high-privilege WordPress account to import the archive and a victim to open the extracted page, exposing that browser session to stored script execution.

The record

CVE
CVE-2021-24378
Published
Jun 21, 2021
Updated
Aug 3, 2024
Vendor
Optimizing Matters
Product
Autoptimize
Classifications
CWE-79, T1203
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jun 21, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=2.7.8 <2.7.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Optimizing Matters · Autoptimizeversion=2.7.8 <2.7.8

Published CVSS scores

4.8NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
3.5NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
4.8WordfenceCVSS:3.1/AV:N/AC:L/PR:H/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
Privilegesadmin
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

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Your stack

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