Threats / Roundcube / CVE-2020-13965
CVE-2020-13965
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Roundcube Webmail vulnerability
Roundcube Webmail contains a cross-site scripting vulnerability via malicious XML attachments, allowing remote attackers to execute arbitrary scripts in user browsers.
Verdict
Today item — known-exploited.
A remote attacker can craft a malicious XML attachment that, when processed by Roundcube Webmail, injects and executes arbitrary JavaScript in the context of a victim's browser session, potentially compromising account credentials or session tokens.
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
2 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2024-06-26).
Probability (EPSS)
EPSS 0.76596 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
Affected: Roundcube, Webmail. Confirm exact fixed builds in the vendor advisory.
Weakness (CWE)
Mapped to CWE-80 CWE-80 — weakness family: Web / client.CWE assignment from the public NVD record; the weakness class drives how the flaw is exploited.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I craft a specially-formed XML attachment and send it to a target user.
Business
Webmail users receive email with embedded malicious content.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I wait for the victim to open or preview the attachment in Roundcube.
Business
User interaction with email attachment triggers vulnerability processing.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary JavaScript in the victim's browser within the Roundcube session context.
Business
Attacker gains ability to steal session cookies, credentials, or perform actions as the authenticated user.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05