Description
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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Roundcube | Webmail | 1.6.0 – < 1.6.18, 1.7.0 – < 1.7.3 | 1.6.18 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | roundcube | 1.6.18+dfsg-1 | — |
| Debian 13 | roundcube | 1.6.18+dfsg-0+deb13u1 | — |
| Debian 12 | roundcube | 1.6.5+dfsg-1+deb12u11 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | roundcube | No fix yet | — |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | roundcube | No fix yet | — |
| Ubuntu Pro 24.04 LTS | roundcube | No fix yet | — |
| Ubuntu Pro 22.04 LTS | roundcube | No fix yet | — |
| Ubuntu Pro 20.04 LTS | roundcube | No fix yet | — |
| Ubuntu Pro 18.04 LTS | roundcube | No fix yet | — |
| Ubuntu Pro 16.04 LTS | roundcube | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | roundcubemail | 1.6.19-1.1 | openSUSE-SU-2026:12169-1 |
| openSUSE Leap 16.0 | roundcubemail | 1.6.20-bp160.1.1 | openSUSE-SU-2026:22195-1 |
Advisories 3
- WID-SEC-2026-2880 Roundcube Webmail: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 1, 2026
- openSUSE-SU-2026:22195-1 Security update for roundcubemail SUSE / openSUSE Security Updates · Nov 1, 2026
- openSUSE-SU-2026:12169-1 roundcubemail-1.6.19-1.1 on GA media SUSE / openSUSE Security Updates · Oct 18, 2026
References
- https://roundcube.net/news/2026/08/09/security-updates-1.6.18-and-1.7.3
- https://github.com/roundcube/roundcubemail/releases/tag/1.6.18
- https://github.com/roundcube/roundcubemail/commit/62d33c8a0dc3fd0dd03984220dc9709e8e0de43b
- https://github.com/roundcube/roundcubemail/releases/tag/1.7.3
- https://github.com/roundcube/roundcubemail/commit/a2334990c02f7cb77b1a8d6fa97fcd9e1b5cd1fb