Exploited CVEs / Roundcube / CVE-2020-13965

CVE-2020-13965

Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted. Federal agencies were required to remediate by 2024-07-17 (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

77%

EPSS exploit probability

Medium

Severity

2024-06-26

Added to KEV

2024-07-17 (past due)

CISA due date

Actively exploited Roundcube Webmail vulnerability, Medium severity, CVSS 6.1. Added to the CISA KEV catalog 2024-06-26.

Senserva AI read on CVE-2020-13965 CISA required action Official fix for CVE-2020-13965 Admin questions

Senserva AI Opinion for CVE-2020-13965

A malicious XML attachment triggers this Roundcube Webmail cross-site scripting flaw, letting attackers manipulate a victim's webmail session through a single hostile email. CISA confirmed exploitation in June 2024, and webmail XSS is a proven technique for silently reading and redirecting mail. The 77 percent EPSS score marks continued attacker interest in self-hosted Roundcube.

Do this: Upgrade Roundcube installations past the CVE-2020-13965 fix and review mailbox filter rules for entries users did not create.

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

Senserva AI Opinion and rich prompt for CVE-2020-13965

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

I run IT security. Facts for CVE-2020-13965, an actively exploited vulnerability (source: https://senserva.com/cve/CVE-2020-13965.html, data from CISA KEV, FIRST.org EPSS, NVD, refreshed twice a day (5 AM and 3 PM US Central)):
- CVE-2020-13965: Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability
- Affected: Roundcube Webmail
- Severity: Medium, CVSS 6.1; EPSS 30-day exploitation probability 77%
- Added to CISA KEV: 2024-06-26; federal remediation due 2024-07-17
- Ransomware-linked: no
- CISA required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.
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 2024-07-17; 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-2020-13965

Published: 2024-06-26
Last revised: 2024-06-26
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

2024-06-26 added to the CISA KEV catalog by CISA
2026-07-17 CVSS 0.0 to 6.1; EPSS first scored at 76.6%

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: 2024-07-17 (past due).

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Official fix for CVE-2020-13965

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

CISA KEV entry

Common questions about CVE-2020-13965

Is CVE-2020-13965 actively exploited?

Yes. CVE-2020-13965 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2024-06-26, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 77%.

What is the CISA deadline and required action for CVE-2020-13965?

CISA set the federal (BOD 22-01) remediation due date at 2024-07-17, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

What fixes CVE-2020-13965?

Check the vendor's security advisory for the patched 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-2020-13965?

Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2020-13965'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-2023-43770 CVE-2023-5631 CVE-2020-12641 CVE-2021-44026
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.