CVE-2020-35730

KEVRoundcube Webmail Cross-Site Scripting (XSS) Vulnerability

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.

An XSS issue was discovered in Roundcube Webmail before 1.2.13, 1.3.x before 1.3.16, and 1.4.x before 1.4.10. The attacker can send a plain text e-mail message, with JavaScript in a link reference element that is mishandled by linkref_addindex in rcube_string_replacer.php.

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

PublishedDec 28, 2020

Last modifiedJun 17, 2026

Added to KEVJun 22, 2023

Remediation dueJul 13, 2023

References

bugs.debian.org/cgi-bin/bugreport.cgi?bug=978491Issue TrackingMailing List
github.com/roundcube/roundcubemail/compare/1.4.9...1.4.10Patch
github.com/roundcube/roundcubemail/releases/tag/1.2.13Release Notes
github.com/roundcube/roundcubemail/releases/tag/1.3.16Release Notes
github.com/roundcube/roundcubemail/releases/tag/1.4.10Release Notes
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HCEU4BM5WGIDJWP6Z4PCH62ZMH57QYM2/Mailing ListRelease Notes
lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/HMLIZWKMTRCLU7KZLEQHELS4INXJ7X5Q/Mailing ListRelease Notes
roundcube.net/download/Product
alexbirnberg.com/roundcube-xss.htmlBroken Link
cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2020-35730US Government Resource

0 recent articles mention this CVE

Risk assessment · High

Actively exploited. Patch immediately.

Exploitation: Confirmed in the wild (CISA KEV)
Federal remediation deadline: Overdue by 1202 days
CVSS: 6.1 MEDIUM
EPSS (30-day exploit probability): 32.9% · top 2% of all CVEs
Weakness: CWE-79
Attack vector: Network, remotely reachable

Recommended actions

1.Apply updates per vendor instructions.
2.Treat as emergency change: patch or isolate internet-facing instances first.
3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.

Assessment is derived automatically from the live signals above; verify against your own asset inventory.