Threats / Roundcube / CVE-2023-43770
CVE-2023-43770
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-06-22
Roundcube Webmail vulnerability
Roundcube Webmail contains a persistent cross-site scripting vulnerability in plain text message handling that enables information disclosure through malicious link references.
Verdict
Today item — known-exploited.
An attacker can inject malicious scripts into plain text email messages. When a victim views the message, the script executes in their browser session, potentially stealing session tokens, credentials, or sensitive email content. The persistent nature means the payload remains in the system.
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Is it exploitable?
— the evidence, ranked above the scoreExploit available
Public proof-of-concept exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
9 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 2024-02-12).
Probability (EPSS)
EPSS 0.56895 — 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-79 Cross-site Scripting (XSS) — 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 an email with embedded XSS payload disguised as a link reference in plain text format.
Business
Attacker gains unauthorized access to user email accounts and sensitive communications stored in Roundcube.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I send the malicious email to a target user who opens it in their Roundcube webmail client.
Business
User session is compromised, enabling account takeover and lateral movement within the organization's email infrastructure.
3
Lateral reach — past segmentation narrative 3
Attacker
I exfiltrate authentication tokens or credentials from the victim's active session.
Business
Confidential business communications and personal data are exposed to unauthorized parties.
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.
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