---
id: "CVE-2020-35730"
kind: "vulnerability"
aliases: ["CVE-2020-35730"]
title: "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"
severity: "high"
cvss: 6.1
epss: null
exploited: true
status: "open"
category: "package"
products: [{"name": "Roundcube Roundcube Webmail", "fixed": [], "affected": "", "ecosystem": "vendor"}, {"name": "roundcube webmail", "fixed": ["1.2.13"], "affected": "< 1.2.13", "ecosystem": "vendor"}, {"name": "roundcube webmail", "fixed": ["1.3.16"], "affected": ">= 1.3.0, < 1.3.16", "ecosystem": "vendor"}, {"name": "roundcube webmail", "fixed": ["1.4.10"], "affected": ">= 1.4, < 1.4.10", "ecosystem": "vendor"}, {"name": "fedoraproject fedora", "fixed": [], "affected": "= 32", "ecosystem": "vendor"}, {"name": "fedoraproject fedora", "fixed": [], "affected": "= 33", "ecosystem": "vendor"}, {"name": "debian linux", "fixed": [], "affected": "= 9.0", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["exploited", "package", "roundcube", "self-hosted", "webmail"]
not_affected_if: ["no-webmail-deployed", "not-roundcube"]
published_at: "2020-12-28T20:15:13+00:00"
first_seen_at: "2026-10-23T19:11:51+00:00"
updated_at: "2026-10-23T22:29:04+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2020-35730", "first_seen_at": "2026-10-23T19:11:51+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2020-35730", "first_seen_at": "2026-10-23T22:29:04+00:00"}]
---

# 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

Roundcube Webmail, a web-based email client, has a cross-site scripting flaw: a plain text email containing JavaScript in a link reference is mishandled, so the script runs in the victim's browser. An attacker who gets a user to open such a message can run script in their Roundcube session and read or act on their mail.

_Summary, check and fix written by a model from the sources; labelled as such._

## Affected

- vendor:Roundcube Roundcube Webmail affected ? fixed ?
- vendor:roundcube webmail affected < 1.2.13 fixed 1.2.13
- vendor:roundcube webmail affected >= 1.3.0, < 1.3.16 fixed 1.3.16
- vendor:roundcube webmail affected >= 1.4, < 1.4.10 fixed 1.4.10
- vendor:fedoraproject fedora affected = 32 fixed ?
- vendor:fedoraproject fedora affected = 33 fixed ?
- vendor:debian linux affected = 9.0 fixed ?

## Fix

Apply the Roundcube update per vendor instructions; the sources do not name the fixed version.
CISA lists this in KEV, so treat it as actively exploited.

## Timeline

- 2026-10-23T19:11:51+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2020-35730
- 2026-10-23T22:29:04+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2020-35730

## From the sources

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.

CISA required action: Apply updates per vendor instructions.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_