Vulnerability

CVE-2020-35730

Medium· 6.1KEVCVSS6.1EPSS67%

.rules3/5

Roundcube Webmail Cross-Site Scripting (XSS) Vulnerability

Roundcube Webmail contains a cross-site scripting (XSS) vulnerability that allows an attacker to send a plain text e-mail message with Javascript in a link reference element that is mishandled by linkref_addinindex in rcube_string_replacer.php.

Threat signal

81/100

High

Severity

medium

CVSS

6.1

EPSS

67%

Active

KEV

CISA KEV — actively exploited

1066d overdue

AffectedRoundcube — Roundcube Webmail

Added to KEV

2023-06-22

Federal patch due (BOD 22-01)

2023-07-13

Required action (CISA verbatim)

Apply updates per vendor instructions.

Vendor advisory + references

CISA description: “Roundcube Webmail contains a cross-site scripting (XSS) vulnerability that allows an attacker to send a plain text e-mail message with Javascript in a link reference element that is mishandled by linkref_addinindex in rcube_string_replacer.php.”

CVSS

v3.1Open in FIRST calculator →

6.1/ 10MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Attack VectorNetworkExploitable remotely over the internet — no local access needed.
Attack ComplexityLowNo special conditions — exploit works reliably.
Privileges RequiredNoneUnauthenticated — no credentials needed.
User InteractionRequiredRequires user action (click, file open, etc).
ScopeChangedImpact extends beyond the vulnerable component (e.g. sandbox escape).
Confidentiality ImpactLowSome data disclosure; attacker doesn't fully control what.
Integrity ImpactLowSome data modification; attacker doesn't fully control extent.
Availability ImpactNoneNo availability impact.

EPSS

Exploit prediction · 30-day horizonFIRST.org →

67.4%

probability of exploitation in next 30 days

p99

higher than 99% of all CVEs

3-day trend↑ 0pp

Statistically about to be weaponized — top-tier triage urgency.

Vendor VEX

No VEX statements published for CVE-2020-35730. Vendors publish VEX (Vulnerability Exploitability eXchange) to assert per-product whether a CVE is actually exploitable in their distribution.

SSVCAttend

Active exploitation with limited impact — coordinate patching

exploitation: active
automatable: no
impact: partial
mission: support

Lifecycle

2023-06-22Added to CISA KEVransomware: Unknown
2023-06-22Published
2023-07-13Federal patch due (BOD 22-01)
2026-06-12Last modified1 source

No source-event history recorded yet. New revisions will appear here as ingestors re-fetch this CVE.