medium Known exploitedREV. 01

CVE-2020-13965Roundcube Webmail — script from a previewed attachment

Roundcube renders attachments of type text/xml in its preview, so a crafted attachment runs script in the reader's session — cross-site scripting (XSS) triggered by nothing more than opening the mail. Fixed in 1.3.12 and 1.4.5.

YOUR NEXT MOVE

Update Roundcube to 1.3.12 or 1.4.5, whichever line you run; both releases stop the preview from rendering the attachment type this abuses.

Read the risk

THE VITAL STATS
CVSS score
6.1/ 10
CVSS v3.1
EPSS probability
77%
Likelihood of exploitation
Attack complexity
Low
Conditions needed to exploit
Known exploited
Yes — CISA KEV
CVE published
2020-06-09
Added to KEV
2024-06-26
Exploit published
Yes
Confidence
high
Kill chain
execution
MITRE ATT&CK
T1059.007
Severity
medium

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attacker needsThe victim must open a message carrying the attachment.

Fixed inRoundcube Webmail >= 1.3.12, Roundcube Webmail >= 1.4.5

Behind the card

5 REFERENCES
Field-level provenanceTRACE THE SOURCES +

Which source supports each field, when it was retrieved, and who extracted it.

FieldsSourceRetrievedExtractorConfidence
cvss, exploitation.attack_complexity, exploitation.exploit_available, references, published_atnvd.nist.gov2026-09-24scrty-crds-pipeline/0.1high
exploitation.known_exploited, exploitation.kev_addedcisa.gov2026-09-24scrty-crds-pipeline/0.1high
epssapi.first.org2026-09-24scrty-crds-pipeline/0.1high
title, summary, severity, remediation, mitre_attack, kill_chain, recommended_action, confidence, tags, exploitation.prerequisitesnvd.nist.gov2026-09-24claude-codehigh

Printing history

THE RECORD
  1. r1Initial base card

First printing. This card has not been reprinted since publication.

crds:cve-2020-13965 · CRDS 0.1 · Issued 2026-09-24