CVE-2023-43770: Roundcube Webmail Persistent Cross-Site Scripting (XSS) Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 12 Feb 2024, 143 days after the CVE record was published.

How likely is exploitation in the next 30 days?

63.7%

EPSS score, percentile 99.2 of all scored records

How severe?

6.1 Medium

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

CISA deadline 4 Mar 2024. Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

The CVE record links no vendor advisory, patch or mitigation.

Which versions are affected?

Not stated. The CVE record gives vendor and product as “n/a” and the version as “unspecified”.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 4 March 2024.

Advisories and patches

The CVE record links no vendor advisory, patch or mitigation.

Linked from CISA's catalog entry

• https://roundcube.net/news/2023/09/15/security-update-1.6.3-released
• https://nvd.nist.gov/vuln/detail/CVE-2023-43770

Affected products and versions

The CVE record does not name affected products or versions: vendor and product are “n/a” and the version is “unspecified”.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Roundcube Webmail contains a persistent cross-site scripting (XSS) vulnerability that can lead to information disclosure via malicious link references in plain/text messages.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2023-43770 to its Known Exploited Vulnerabilities (KEV) catalog on 12 Feb 2024.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 4 Mar 2024.
• The CVE record was published on 22 Sep 2023, 143 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 6.1 (Medium), taken from CISA's enrichment of the record.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 63.7% (percentile 99.2), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable no, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

Roundcube before 1.4.14, 1.5.x before 1.5.4, and 1.6.x before 1.6.3 allows XSS via text/plain e-mail messages with crafted links because of program/lib/Roundcube/rcube_string_replacer.php behavior.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• github.com
• roundcube.net
• [debian-lts-announce] 20230922 [SECURITY] [DLA 3577-1] roundcube security update

More exploited Roundcube vulnerabilities

• CVE-2025-49113: RoundCube Webmail Deserialization of Untrusted Data Vulnerability (added 20 Feb 2026)
• CVE-2025-68461: RoundCube Webmail Cross-site Scripting Vulnerability (added 20 Feb 2026)
• CVE-2024-42009: RoundCube Webmail Cross-Site Scripting Vulnerability (added 9 Jun 2025)
• CVE-2024-37383: RoundCube Webmail Cross-Site Scripting (XSS) Vulnerability (added 24 Oct 2024)
• CVE-2020-13965: Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability (added 26 Jun 2024)
• CVE-2023-5631: Roundcube Webmail Persistent Cross-Site Scripting (XSS) Vulnerability (added 26 Oct 2023)