Roundcube Webmail up to 1.6.17/1.7.2 CSS Proxy cross site scripting

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.6$0-$5k0.21

Summaryinfo

A vulnerability described as problematic has been identified in Roundcube Webmail up to 1.6.17/1.7.2. Affected by this vulnerability is an unknown functionality of the component CSS Proxy. Executing a manipulation can lead to cross site scripting. This vulnerability is registered as CVE-2026-74998. It is possible to launch the attack remotely. No exploit is available.

Detailsinfo

A vulnerability has been found in Roundcube Webmail up to 1.6.17/1.7.2 and classified as problematic. This vulnerability affects an unknown code block of the component CSS Proxy. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is 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. As an impact it is known to affect integrity. CVE summarizes:

In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, responses from the CSS (Cascading Style Sheets) proxy were not validated, which may result in information disclosure or XSS (cross-site scripting) via MIME sniffing.

The advisory is available at roundcube.net. This vulnerability was named CVE-2026-74998 since 08/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. 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 1.6.18 or 1.7.3 eliminates this vulnerability.

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Productinfo

Type

Vendor

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.7
VulDB Meta Temp Score: 5.6

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.2
CNA Vector (MITRE): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
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: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Webmail 1.6.18/1.7.3

Timelineinfo

08/17/2026 Advisory disclosed
08/17/2026 +0 days CVE reserved
08/17/2026 +0 days VulDB entry created
08/17/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: roundcube.net
Status: Confirmed

CVE: CVE-2026-74998 (🔒)
GCVE (CVE): GCVE-0-2026-74998
GCVE (VulDB): GCVE-100-391270

Entryinfo

Created: 08/17/2026 15:15
Changes: 08/17/2026 15:15 (64)
Complete: 🔍
Cache ID: 216::103

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