Vulnerability · Published Aug 17, 2026 · Assigned by mitre
CVE-2026-74998
High 7.2
In plain English
A high-severity cross-site scripting in Webmail from Roundcube. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 25% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.2High
Exploit odds (30 days)0.3%top 74.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | roundcube | 1.6.5+dfsg-1+deb12u11 | DEBIAN-CVE-2026-74998 |
| Debian:13 | roundcube | 1.6.18+dfsg-0+deb13u1 | DEBIAN-CVE-2026-74998 |
| Debian:14 | roundcube | 1.6.18+dfsg-1 | DEBIAN-CVE-2026-74998 |
| Ubuntu:26.10 | roundcube | no fix listed | UBUNTU-CVE-2026-74998 |
Affected products (as reported)
Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
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