CVE-2026-35539 | Roundcube Webmail up to 1.5.13/1.6.13 HTML Attachment HTML injection

VDB-355062 · CVE-2026-35539 · GCVE-0-2026-35539 ROUNDCUBE WEBMAIL UP TO 1.5.13/1.6.13 HTML ATTACHMENT HTML INJECTION HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 5.1 $0-$5k 1.38 Summaryinfo A vulnerability categorized as problematic has been discovered in Roundcube Webmail up to 1.5.13/1.6.13. This issue affects some unknown processing of the component HTML Attachment Handler. The manipulation results in HTML injection. This vulnerability is reported as CVE-2026-35539. The attack can be launched remotely. No exploit exists. It is advisable to upgrade the affected component. Detailsinfo A vulnerability, which was classified as problematic, was found in Roundcube Webmail up to 1.5.13/1.6.13. Affected is an unknown functionality of the component HTML Attachment Handler. The manipulation with an unknown input leads to a html injection vulnerability. CWE is classifying the issue as CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. This is going to have an impact on integrity. CVE summarizes: An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. XSS exists because of insufficient HTML attachment sanitization in preview mode. A victim must preview a text/html attachment. The advisory is available at roundcube.net. This vulnerability is traded as CVE-2026-35539 since 04/03/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1059.007 by the MITRE ATT&CK project. Upgrading to version 1.5.14 or 1.6.14 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 10a6d1fa8acac85c727b0a6ae4a6642bfa27bea1 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version. Productinfo Type Mail Client Software Vendor Roundcube Name Webmail Version 1.5.0 1.5.1 1.5.2 1.5.3 1.5.4 1.5.5 1.5.6 1.5.7 1.5.8 1.5.9 1.5.10 1.5.11 1.5.12 1.5.13 1.6.0 1.6.1 1.6.2 1.6.3 1.6.4 1.6.5 1.6.6 1.6.7 1.6.8 1.6.9 1.6.10 1.6.11 1.6.12 1.6.13 License free CPE 2.3info 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 5.2 VulDB Meta Temp Score: 5.1 VulDB Base Score: 4.3 VulDB Temp Score: 4.1 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 6.1 CNA Vector (MITRE): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: HTML injection CWE: CWE-79 / CWE-94 / CWE-74 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: Webmail 1.5.14/1.6.14 Patch: 10a6d1fa8acac85c727b0a6ae4a6642bfa27bea1 Timelineinfo 04/03/2026 Advisory disclosed 04/03/2026 +0 days CVE reserved 04/03/2026 +0 days VulDB entry created 04/03/2026 +0 days VulDB entry last update Sourcesinfo Advisory: roundcube.net Status: Confirmed CVE: CVE-2026-35539 (🔒) GCVE (CVE): GCVE-0-2026-35539 GCVE (VulDB): GCVE-100-355062 Entryinfo Created: 04/03/2026 07:47 Changes: 04/03/2026 07:47 (68) Complete: 🔍 Cache ID: 99:86D:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸