Stored XSS in Roundcube Webmail linkref_addindex
CVE-2020-35730 is a stored cross-site scripting vulnerability in Roundcube Webmail affecting versions before 1.2.13, 1.3.x before 1.3.16, and 1.4.x before 1.4.10. The issue is triggered when an attacker sends a plain-text email containing JavaScript in a link reference element. Roundcube mishandles this content in linkref_addindex within rcube_string_replacer.php, allowing attacker-controlled script to be rendered and executed in the context of the victim’s Roundcube webmail session when the message is viewed. Reporting cited in the provided content indicates the flaw has been exploited in espionage campaigns to run arbitrary JavaScript in the victim’s browser and access mailbox data.
Are you exposed to this one?
Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.
Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A medium-severity cross-site scripting (XSS) vulnerability in Roundcube webmail software that allows attackers to execute malicious JavaScript in the context of the victim's browser session.
A stored cross-site scripting (XSS) vulnerability in Roundcube webmail that allows attacker-supplied JavaScript embedded in an email body to execute in the victim’s webmail session context when the email is viewed, enabling credential and email data theft.
A Roundcube webmail vulnerability reportedly abused by APT28 for reconnaissance and data gathering.
An older Roundcube Webmail XSS vulnerability reported as exploited by Winter Vivern (Aug–Sep 2023) and also exploited by Sednit/APT28 against similar targets.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.