What is the CVSS score of CVE-2026-35543?

CVE-2026-35543 has a CVSS 3.1 base score of 5.3 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N. EPSS exploitation probability: 0.0%.

Is there a patch available for CVE-2026-35543?

Yes, a patch is available for CVE-2026-35543. Update the affected software to the latest version immediately.

Roundcube CVE-2026-35543

EUVD-2026-18589 MEDIUM

Incorrect Resource Transfer Between Spheres (CWE-669)

2026-04-03 mitre

GHSA-j2g6-8rvg-7mf6

Information Disclosure Roundcube Webmail

5.3

CVSS 3.1 · Vendor: mitre

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Vulnerability Assessment

Weakness	CWE CWE-669 ASVS 5.0 V15 - Secure Coding and Architecture Incorrect resource transfer between spheres
Impact	The CVSS vector (AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N) indicates a network-accessible vulnerability requiring no privileges or user interaction, but with low confidentiality impact and no integrity or availability damage. The moderate CVSS score of 5.3 reflects this limited scope. From a real-world risk perspective, this is a practical concern for Roundcube deployments because: (1) email-based attacks are common and do not require special attacker capabilities, (2) the no-authentication and no-user-interaction requirements mean any email sender can exploit it, and (3) information disclosure through tracking pixel bypass could expose user behavior patterns to threat actors. However, the vulnerability does not enable remote code execution, account takeover, or denial of service, limiting its criticality. The access-control-bypass and information-disclosure impacts align with the CWE-669 classification and represent the primary real-world concern for privacy-conscious deployments.
Exploit ScenarioDerived	An attacker sends a specially crafted HTML email to a Roundcube Webmail user containing an SVG element with animate attributes designed to fetch a remote tracking image or script. When the recipient opens the email, Roundcube's image blocking feature fails to recognize the SVG animate construct as a remote resource request, allowing the embedded SVG animation to execute and contact the attacker's server. This reveals the recipient's email open event and IP address, bypassing the intended privacy protection that remote image blocking provides. No complex attack prerequisites or user interaction beyond opening the email is required.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – Apr 03, 2026

Roundcube Webmail before versions 1.5.14 and 1.6.14 allows unauthenticated remote attackers to bypass the remote image blocking feature via SVG content containing animate attributes in email messages, leading to information disclosure or access control bypass. The vulnerability has a CVSS score of 5.3 (moderate severity) with low attack complexity and no authentication required, though the confidentiality impact is limited.

RemediationAI

Organizations must upgrade Roundcube Webmail to version 1.5.14, 1.6.14, or later to remediate the vulnerability. Vendor-released patches are available as follows: version 1.5.14 (commit 1a63e01542bff42aaa71c00c4c279a09ef31f20c), version 1.6.14 (commit 39471343ee081ce1d31696c456a2c163462daae3), and version 1.7-rc5 (commit 82ab5eca7b332fce7a174b2b987f0957a66377cd). Administrators should apply the patch corresponding to their current version branch to restore proper SVG content filtering in the email display pipeline. See the official Roundcube security advisory at https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14 for detailed upgrade instructions and release notes.

Affected VersionsENISA

Webmail 1.6.0 <1.6.14

Webmail 0 <1.5.14

Affected Packages

composer roundcube/roundcubemail fix: 1.7-rc5

euvd webmail fix: 1.5.14, 1.6.14

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in composer, euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Roundcube Webmail implements a remote image blocking feature to prevent tracking and protect user privacy when displaying HTML emails. The vulnerability exists in the image filtering mechanism, which fails to properly sanitize SVG (Scalable Vector Graphics) elements that contain animate attributes. SVG is an XML-based vector image format that can embed JavaScript-like behavior through animation directives, allowing attackers to circumvent content security controls. The root cause is classified under CWE-669 (Improper Access Control), indicating the filtering logic does not adequately enforce its intended security policy for all vector graphic formats. The vulnerability affects Roundcube Webmail versions before 1.5.14 (all 1.5.x versions) and before 1.6.14 (all 1.6.x versions up to 1.6.13), as identified via CPE cpe:2.3:a:roundcube:webmail.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (mitre) PRIMARY 5.3 MEDIUM

AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Primary rating from Vendor (mitre) · only source for this CVE.

CVSS VectorVendor: mitre

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Lifecycle Timeline

Patch released

Apr 04, 2026 - 08:30 nvd

Patch available

CVE Published

Apr 03, 2026 - 03:57 nvd

MEDIUM 5.3

DescriptionCVE.org

An issue was discovered in Roundcube Webmail before 1.5.14 and 1.6.14. The remote image blocking feature can be bypassed via SVG content (with animate attributes) in an e-mail message. This may lead to information disclosure or access-control bypass.

Threat Intelligence Overview

EPSS Score

0.0%

Top 90% exploitable

Threat Intel

1 source

Data Quality

7 sources

Confidence: High

EUVD

NVD

CVE.org

EPSS

Vulnrichment GHSA

GitHub

VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC No

EPSS 0.0%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation

None

System Exposure· derived

Open

Automatable

Yes

Human Impact· derived

Medium

Technical Impact

Partial

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +26

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Information Disclosure MEDIUM

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.