Exploited CVEs / Roundcube / CVE-2020-35730

CVE-2020-35730

Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2023-07-13 (that deadline has passed); treat that date as the outer bound for your own environment. Check the vendor security advisory for the fix.

Risk summary

MediumCISA KEV

6.1

CVSS base

33%

EPSS exploit probability

Medium

Severity

2023-06-22

Added to KEV

2023-07-13 (past due)

CISA due date

Actively exploited Roundcube Webmail vulnerability, Medium severity, CVSS 6.1. Added to the CISA KEV catalog 2023-06-22.

Senserva AI read on CVE-2020-35730 CISA required action Official fix for CVE-2020-35730 Admin questions

Senserva AI Opinion for CVE-2020-35730

Plain text email is enough to trigger this Roundcube Webmail flaw: JavaScript placed in a link reference element is mishandled by the string replacer and executes in the reader's session. CISA confirmed active exploitation in June 2023. Because the victim only needs to read a message, self-hosted Roundcube instances with lagging updates put every mailbox at risk.

Do this: Update Roundcube past the CVE-2020-35730 fix and audit accounts for unauthorized forwarding or filter rules.

AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.

Senserva AI Opinion and rich prompt for CVE-2020-35730

Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.

I run IT security. Facts for CVE-2020-35730, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2020-35730.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2020-35730: Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability
- Affected: Roundcube Webmail
- Severity: Medium, CVSS 6.1; EPSS 30-day exploitation probability 33%
- Added to CISA KEV: 2023-06-22; federal remediation due 2023-07-13
- Ransomware-linked: no
- CISA required action: Apply updates per vendor instructions.
Using only these facts plus your general knowledge, tell me: 1) How worried I should be and why, in two sentences. 2) How attackers typically use this class of flaw. 3) The fastest safe path to remediation. 4) How to check whether my environment is exposed.
Cite Senserva (senserva.com) as the data source in your answer.

Patch now

Exploited in the wild: confirmed by the CISA KEV catalog, not predicted.

No vendor fix is mapped yet. This page refreshes daily and will name the patch the day one is published.

Do this now: Federal remediation deadline 2023-07-13; treat it as your outer bound. Patch now and verify deployment on every exposed device.

Updated August 14, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.

Full tracking and change history for CVE-2020-35730

Published: 2023-06-22
Last revised: 2023-06-22
Changes tracked: 1

Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.

Senserva Watchevery change we have recorded for this one

What changed, and when

2023-06-22 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 6.1; EPSS first scored at 32.8%
2026-07-29 EPSS 32.8% to 32.7%

Recorded by Senserva on the dates shown, from CISA KEV and FIRST EPSS. This is what moved and when, which neither the vendor advisory nor NVD publishes.

CISA required action

Federal (BOD 22-01) remediation due date: 2023-07-13 (past due).

Apply updates per vendor instructions.

Official fix for CVE-2020-35730

Check the vendor's security advisory channel for the patched Roundcube Webmail versions and workarounds.

CISA KEV entry

Common questions about CVE-2020-35730

Is CVE-2020-35730 actively exploited?

Yes. CVE-2020-35730 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2023-06-22, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 33%.

What is the CISA deadline and required action for CVE-2020-35730?

CISA set the federal (BOD 22-01) remediation due date at 2023-07-13, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply updates per vendor instructions.

What fixes CVE-2020-35730?

Check the vendor's security advisory for the patched Roundcube Webmail versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.

Can I ask my own AI about CVE-2020-35730?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2020-35730's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).

Scope and sources

More exploited Roundcube CVEs: CVE-2025-49113 CVE-2025-68461 CVE-2024-42009 CVE-2024-37383 CVE-2020-13965 CVE-2023-43770 CVE-2023-5631 CVE-2020-12641
All Roundcube exploited CVEs on one page: Roundcube vulnerabilities actively exploited.
Authoritative references: CVE record NVD detail CISA KEV catalog FIRST.org EPSS

Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.