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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… (CVE-2026-74998)

0
Medium
VulnerabilityCVE-2026-74998gcveosvubuntu-cve-2026-74998cve-2026-74998ubuntu-pro-16-04-ltsubuntu-pro-18-04-ltsubuntu-pro-20-04-ltsubuntu-pro-22-04-ltsubuntu-pro-24-04-ltsubuntu-26-10ubuntu-pro-26-04-lts
Published: 08/17/2026 (08/17/2026, 13:16:00 UTC)
Source: GCVE Database
Product: roundcube

Description

Roundcube Webmail versions before 1.6.18 and 1.7.x before 1.7.3 contain a vulnerability where responses from the CSS proxy are not validated. This flaw may lead to information disclosure or cross-site scripting (XSS) attacks via MIME sniffing.

CVSS v3.1

Score 7.2high

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

Affected software

Ubuntu:Pro:16.04:LTSmore threats →ghsa
roundcube
pkg:deb/ubuntu/roundcube?arch=source&distro=esm-apps/xenial
Affected versions
=1.1.1+dfsg.1-2=1.1.2+dfsg.1-5=1.1.3+dfsg.1-1=1.1.4+dfsg.1-1=1.2~beta+dfsg.1-0ubuntu1=1.2~beta+dfsg.1-0ubuntu1+esm1=1.2~beta+dfsg.1-0ubuntu1+esm2=1.2~beta+dfsg.1-0ubuntu1+esm3=1.2~beta+dfsg.1-0ubuntu1+esm4=1.2~beta+dfsg.1-0ubuntu1+esm5=1.2~beta+dfsg.1-0ubuntu1+esm6=1.2~beta+dfsg.1-0ubuntu1+esm7=1.2~beta+dfsg.1-0ubuntu1+esm8
Ubuntu:Pro:18.04:LTSmore threats →ghsa
roundcube
pkg:deb/ubuntu/roundcube?arch=source&distro=esm-apps/bionic
Affected versions
=1.3.0+dfsg.1-1=1.3.1+dfsg.1-1=1.3.3+dfsg.1-1=1.3.3+dfsg.1-2=1.3.6+dfsg.1-1=1.3.6+dfsg.1-1ubuntu0.1~esm1=1.3.6+dfsg.1-1ubuntu0.1~esm2=1.3.6+dfsg.1-1ubuntu0.1~esm3=1.3.6+dfsg.1-1ubuntu0.1~esm4=1.3.6+dfsg.1-1ubuntu0.1~esm5=1.3.6+dfsg.1-1ubuntu0.1~esm6=1.3.6+dfsg.1-1ubuntu0.1~esm7=1.3.6+dfsg.1-1ubuntu0.1~esm8
Ubuntu:Pro:20.04:LTSmore threats →ghsa
roundcube
pkg:deb/ubuntu/roundcube?arch=source&distro=esm-apps/focal
Affected versions
=1.3.8+dfsg.1-2=1.3.10+dfsg.1-1=1.4.1+dfsg.1-2=1.4.2+dfsg.1-1=1.4.2+dfsg.1-2=1.4.3+dfsg.1-1=1.4.3+dfsg.1-1ubuntu0.1~esm1=1.4.3+dfsg.1-1ubuntu0.1~esm2=1.4.3+dfsg.1-1ubuntu0.1~esm3=1.4.3+dfsg.1-1ubuntu0.1~esm4=1.4.3+dfsg.1-1ubuntu0.1~esm5=1.4.3+dfsg.1-1ubuntu0.1~esm6=1.4.3+dfsg.1-1ubuntu0.1~esm7=1.4.3+dfsg.1-1ubuntu0.1~esm8
Ubuntu:Pro:22.04:LTSmore threats →ghsa
roundcube
pkg:deb/ubuntu/roundcube?arch=source&distro=esm-apps/jammy
Affected versions
=1.4.11+dfsg.1-4=1.5.0+dfsg.1-2=1.5.0+dfsg.1-2ubuntu0.1~esm1=1.5.0+dfsg.1-2ubuntu0.1~esm2=1.5.0+dfsg.1-2ubuntu0.1~esm3=1.5.0+dfsg.1-2ubuntu0.1~esm4=1.5.0+dfsg.1-2ubuntu0.1~esm5=1.5.0+dfsg.1-2ubuntu0.1~esm6
Ubuntu:Pro:24.04:LTSmore threats →ghsa
roundcube
pkg:deb/ubuntu/roundcube?arch=source&distro=esm-apps/noble
Affected versions
=1.6.2+dfsg-1=1.6.4+dfsg-1=1.6.5+dfsg-1=1.6.6+dfsg-1=1.6.6+dfsg-2=1.6.6+dfsg-2ubuntu0.1=1.6.6+dfsg-2ubuntu0.1+esm1=1.6.6+dfsg-2ubuntu0.1+esm2=1.6.6+dfsg-2ubuntu0.1+esm3
Ubuntu:26.10more threats →ghsa
roundcube
pkg:deb/ubuntu/roundcube?arch=source&distro=stonking
Affected versions
=1.6.11+dfsg-1
Ubuntu:Pro:26.04:LTSmore threats →ghsa
roundcube
pkg:deb/ubuntu/roundcube?arch=source&distro=esm-apps/resolute
Affected versions
=1.6.11+dfsg-1=1.6.11+dfsg-1ubuntu0.26.04.1~esm1

Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.

AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 10/17/2026, 23:46:16 UTC

Technical Analysis

In Roundcube Webmail versions prior to 1.6.18 and 1.7.x prior to 1.7.3, the CSS proxy responses lack proper validation. This vulnerability can be exploited to cause information disclosure or cross-site scripting (XSS) through MIME sniffing, potentially allowing attackers to execute malicious scripts or access sensitive information.

Potential Impact

The vulnerability allows attackers to potentially disclose information or execute cross-site scripting attacks by exploiting unvalidated CSS proxy responses. This can compromise confidentiality and integrity of user data within the affected Roundcube Webmail instances.

Mitigation Recommendations

A fix is available in Roundcube Webmail versions 1.6.18 and 1.7.3 and later. Users should upgrade to these versions or newer to remediate this vulnerability. No additional mitigation steps are indicated.

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Technical Details

Gcve Source
db.gcve.eu
Osv Id
UBUNTU-CVE-2026-74998
Osv Schema Version
1.7.0
Ecosystems
["Ubuntu:Pro:16.04:LTS","Ubuntu:Pro:18.04:LTS","Ubuntu:Pro:20.04:LTS","Ubuntu:Pro:22.04:LTS","Ubuntu:Pro:24.04:LTS","Ubuntu:26.10","Ubuntu:Pro:26.04:LTS"]
Cvss Version
3.1
State
PUBLISHED

Threat ID: 6ad3f5842cdf04f65666218d

Added to database: 10/17/2026, 22:24:04 UTC

Last enriched: 10/17/2026, 23:46:16 UTC

Last updated: 10/17/2026, 23:46:16 UTC

Views: 2

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