What is CVE-2024-42009?

CVE-2024-42009 is a critical-severity vulnerability in Roundcube Webmail, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2024-08-05.

How severe is CVE-2024-42009?

Critical severity. CVSS v3 base score is 9.3 out of 10.

Is CVE-2024-42009 known to be exploited?

Yes. CVE-2024-42009 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-06-09), indicating it is being actively exploited. 15 public proof-of-concept repositories are indexed.

XSS in Roundcube Webmail

CVE-2024-42009

A Cross-Site Scripting vulnerability in Roundcube through 1.5.7 and 1.6.x through 1.6.7 allows a remote attacker to steal and send emails of a victim via a crafted e-mail message that abuses a Desanitization issue in message_body() in program/actions/mail/show.php.

Vulnerability class: XSS (Cross-Site Scripting)

Published 2024-08-05 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.3 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.829 (99.7th percentile), scored 2026-10-16.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.829 · newest: 0.829 · change: 0.000

Affected products

Roundcube Webmail

Weakness classification (CWE)

CWE-79 — Cross-site Scripting

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2025-06-09. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2025-06-30.

Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Public proof-of-concept exploits

References

github.com/roundcube/roundcubemail/releases (Release Notes)
sonarsource.com/blog/government-emails-at-risk-critical-cross-site-scripting-vu… (Technical Description, Third Party Advisory)
github.com/roundcube/roundcubemail/releases/tag/1.5.8 (Release Notes)
github.com/roundcube/roundcubemail/releases/tag/1.6.8 (Release Notes)
roundcube.net/news/2024/08/04/security-updates-1.6.8-and-1.5.8 (Vendor Advisory)
134c704f-9b21-4f2e-91b3-4a467353bcc0 (US Government Resource)

Frequently asked questions

What is CVE-2024-42009?: CVE-2024-42009 is a critical-severity vulnerability in Roundcube Webmail, classified under Cross-site Scripting. CVSS score: 9.3/10. Published 2024-08-05.
How severe is CVE-2024-42009?: Critical severity. CVSS v3 base score is 9.3 out of 10.
Is CVE-2024-42009 known to be exploited?: Yes. CVE-2024-42009 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2025-06-09), indicating it is being actively exploited. 15 public proof-of-concept repositories are indexed.