How severe is CVE-2020-35730?

CVE-2020-35730 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2020-35730 being actively exploited?

Yes. CVE-2020-35730 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2023-06-22, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2020-35730?

CVE-2020-35730 primarily affects Roundcube Webmail. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-35730?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2020-35730 have an EU (EUVD) identifier?

Yes. CVE-2020-35730 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2020-23386. It is also flagged as exploited in the EUVD (since 2023-06-22).

When was CVE-2020-35730 published?

CVE-2020-35730 was published on 2020-12-28 and last updated on 2026-06-17.

CVE-2020-35730

CVE-2020-35730 is a medium-severity vulnerability in Roundcube Webmail with a CVSS 3.x base score of 6.1. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2023-06-22). The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 33% (98th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2023-06-22)
EU (EUVD) id: EUVD-2020-23386
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2023-06-22)
Weakness: CWE-79
Affected product: Roundcube Webmail
Published: 2020-12-28
Last modified: 2026-06-17

Description

An XSS issue was discovered in Roundcube Webmail before 1.2.13, 1.3.x before 1.3.16, and 1.4.x before 1.4.10. The attacker can send a plain text e-mail message, with JavaScript in a link reference element that is mishandled by linkref_addindex in rcube_string_replacer.php.

Frequently asked questions

What is CVE-2020-35730?: An XSS issue was discovered in Roundcube Webmail before 1.2.13, 1.3.x before 1.3.16, and 1.4.x before 1.4.10. The attacker can send a plain text e-mail message, with JavaScript in a link reference element that is mishandled by linkref_addindex in rcube_string_replacer.php.
How severe is CVE-2020-35730?: CVE-2020-35730 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2020-35730 being actively exploited?: Yes. CVE-2020-35730 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2023-06-22, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2020-35730?: CVE-2020-35730 primarily affects Roundcube Webmail. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-35730?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2020-35730 have an EU (EUVD) identifier?: Yes. CVE-2020-35730 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2020-23386. It is also flagged as exploited in the EUVD (since 2023-06-22).
When was CVE-2020-35730 published?: CVE-2020-35730 was published on 2020-12-28 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

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