CVE-2024-42009Known exploitationPublic exploitNetwork attack vector

Email theft via post-sanitization attribute rewriting

Published Aug 5, 2024 · Updated Oct 21, 2025

Stored cross-site scripting in Roundcube Webmail 1.5.7 and earlier and 1.6.0 through 1.6.7 allows remote attackers to execute JavaScript. The message_body() path passes sanitized email HTML to html4inline(), whose loose legacy-attribute regex can unbalance quotes and expose a hidden event handler. Viewing the crafted email triggers the payload in the authenticated webmail origin, allowing theft of email, contacts, or credentials and email sending as the victim.

CVSS severity9.3
Critical
EPSS probability82.88%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Roundcube Webmail 1.5.7 and earlier and 1.6.0 through 1.6.7 allows remote attackers to execute JavaScript. The message_body() path passes sanitized email HTML to html4inline(), whose loose legacy-attribute regex can unbalance quotes and expose a hidden event handler. Viewing the crafted email triggers the payload in the authenticated webmail origin, allowing theft of email, contacts, or credentials and email sending as the victim.

The record

CVE
CVE-2024-42009
Published
Aug 5, 2024
Updated
Oct 21, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 5, 2024CVE publishedPublication date reported by the CVE source.
  2. Oct 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.3CISACVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
9.3NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/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 exploitationReported
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.

Reported exploitation

Technologies

Your stack

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Your stack

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