Threats / Roundcube / CVE-2024-42009
CVE-2024-42009
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Roundcube Webmail vulnerability
Roundcube Webmail contains a cross-site scripting vulnerability in message display that allows remote attackers to steal and send victim emails via crafted messages.
Verdict
Today item — known-exploited.
A reflected XSS flaw in the mail show action enables attackers to inject malicious scripts through specially crafted emails. Successful exploitation permits session hijacking, credential theft, and unauthorized email operations on behalf of victims.
CISA KEV Yes · 2025-06-094EPSS 0.79624 (verify live)5Exploit Weaponized · public PoC6CVSS 9.3 (CISA)3CISA SSVC Exploitation: active · Automatable: no · Impact: total3
01
Is it exploitable?
— the evidence, ranked above the scoreExploit available
Fully weaponized — public exploit code is cataloged for this vulnerability.We link the existence of the exploit; we do not host or redistribute payloads.
Reported exploitation
13 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 2025-06-09).
Probability (EPSS)
EPSS 0.79624 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 9.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N) · Affected: Roundcube, Webmail. Confirm exact fixed builds in the vendor advisory.CVSS — CISA-assigned via the ADP container (CVE.org), version 3.1; the CNA left no metrics, so CISA's own score is used ahead of NVD.
Weakness (CWE)
Mapped to CWE-79 Cross-site Scripting (XSS) — weakness family: Web / client.CWE assignment from the public NVD record (may be stale); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 308 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
Public exploit available
Public exploit tooling is catalogued for this CVE (a public proof-of-concept / detection template). Catalog entries: nuclei template. We link the catalog page(s) only — no payload or code is hosted or restated here.Link, never host — the catalog page is the source; basicsecurity.net does not redistribute payloads.
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 malicious email containing XSS payload targeting the message_body() desanitization flaw.
Business
Attacker gains ability to execute arbitrary JavaScript in victim's browser session.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I send the crafted email to a target user who opens it in Roundcube Webmail.
Business
Victim's session becomes compromised when the email is rendered without proper sanitization.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute JavaScript to steal session tokens or credentials from the victim's browser.
Business
Attacker obtains authenticated access to the victim's email account and mailbox.
4
Data at risk — exfiltration narrative 4
Attacker
I use the compromised session to read, compose, and send emails as the victim.
Business
Confidential communications are exposed and the victim's identity is used for further attacks or fraud.
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