Medium severity6.1NVD Advisory· Published Apr 3, 2026· Updated Apr 7, 2026
CVE-2026-35539
CVE-2026-35539
Description
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.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
roundcube/roundcubemailPackagist | >= 1.7-beta, < 1.7-rc5 | 1.7-rc5 |
Affected products
1Patches
310a6d1fa8acaFix XSS issue in a HTML attachment preview
2 files changed · +4 −0
CHANGELOG.md+1 −0 modified@@ -9,6 +9,7 @@ - Security: Fix remote image blocking bypass via various SVG animate attributes - Security: Fix remote image blocking bypass via a crafted body background attribute - Security: Fix fixed position mitigation bypass via use of !important +- Security: Fix XSS issue in a HTML attachment preview ## Release 1.6.13
program/include/rcmail_action.php+3 −0 modified@@ -691,6 +691,9 @@ public static function display_uploaded_file($file) header('Content-Type: ' . $file['mimetype']); header('Content-Length: ' . $file['size']); + // Use strict security policy to make sure no javascript is executed + header("Content-Security-Policy: script-src 'none'"); + if (isset($file['data']) && is_string($file['data'])) { echo $file['data']; }
1b30edf53696Fix XSS issue in a HTML attachment preview
2 files changed · +4 −0
CHANGELOG.md+1 −0 modified@@ -15,6 +15,7 @@ This file includes only changes we consider noteworthy for users, admins and plu - Security: Fix remote image blocking bypass via various SVG animate attributes - Security: Fix remote image blocking bypass via a crafted body background attribute - Security: Fix fixed position mitigation bypass via use of !important +- Security: Fix XSS issue in a HTML attachment preview ## 1.7-rc4
program/lib/Roundcube/rcube_uploads.php+3 −0 modified@@ -255,6 +255,9 @@ public function display_uploaded_file($file, $thumbnail = false) header('Content-Type: ' . $file['mimetype']); header('Content-Length: ' . $file['size']); + // Use strict security policy to make sure no javascript is executed + header("Content-Security-Policy: script-src 'none'"); + if (isset($file['data']) && is_string($file['data'])) { echo $file['data']; } elseif (!empty($file['path'])) {
d742954ccbcdFix XSS issue in a HTML attachment preview
2 files changed · +4 −0
CHANGELOG.md+1 −0 modified@@ -8,6 +8,7 @@ - Security: Fix remote image blocking bypass via various SVG animate attributes - Security: Fix remote image blocking bypass via a crafted body background attribute - Security: Fix fixed position mitigation bypass via use of !important +- Security: Fix XSS issue in a HTML attachment preview ## Release 1.5.13
program/include/rcmail_action.php+3 −0 modified@@ -683,6 +683,9 @@ public static function display_uploaded_file($file) header('Content-Type: ' . $file['mimetype']); header('Content-Length: ' . $file['size']); + // Use strict security policy to make sure no javascript is executed + header("Content-Security-Policy: script-src 'none'"); + if (isset($file['data']) && is_string($file['data'])) { echo $file['data']; }
Vulnerability mechanics
Generated by null/stub on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
9- github.com/roundcube/roundcubemail/commit/10a6d1fa8acac85c727b0a6ae4a6642bfa27bea1nvdPatchWEB
- github.com/roundcube/roundcubemail/commit/1b30edf5369668c92fe91dae3d52e477c808aa4fnvdPatchWEB
- github.com/roundcube/roundcubemail/commit/d742954ccbcdee7020f8f2e7c49ce0fca5a0efabnvdPatchWEB
- github.com/advisories/GHSA-x4q5-8j5g-hpjcghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-35539ghsaADVISORY
- roundcube.net/news/2026/03/18/security-updates-1.7-rc5-1.6.14-1.5.14nvdVendor AdvisoryWEB
- github.com/roundcube/roundcubemail/releases/tag/1.5.14nvdRelease NotesWEB
- github.com/roundcube/roundcubemail/releases/tag/1.6.14nvdRelease NotesWEB
- github.com/roundcube/roundcubemail/releases/tag/1.7-rc5nvdRelease NotesWEB
News mentions
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