medium Known exploitedREV. 01

CVE-2023-43770Roundcube — a link in plain text mail that runs script

Roundcube rewrites links found in plain text messages into markup without cleaning them, so a crafted message runs script in the reader's session — cross-site scripting (XSS) that sits in the mailbox until opened. Fixed in 1.4.14, 1.5.4 and 1.6.3.

YOUR NEXT MOVE

Update Roundcube to 1.4.14, 1.5.4 or 1.6.3, whichever line you run. The flaw lives in the link rewriter, so no setting takes it out of the path.

Read the risk

THE VITAL STATS
CVSS score
6.1/ 10
CVSS v3.1
EPSS probability
64%
Likelihood of exploitation
Attack complexity
Low
Conditions needed to exploit
Known exploited
Yes — CISA KEV
CVE published
2023-09-22
Added to KEV
2024-02-12
Exploit published
Not recorded
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 the message.

Fixed inRoundcube >= 1.4.14, Roundcube >= 1.5.4, Roundcube >= 1.6.3

Behind the card

3 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-2023-43770 · CRDS 0.1 · Issued 2026-09-24