CRLF injection in Roundcube Webmail - #VU162689
Published: November 9, 2026
Vulnerability identifier: #VU162689
CSH Severity: Low
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
CVE-ID: N/A
CWE-ID: CWE-93
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to inject unintended mail headers into a message disposition notification.
The vulnerability exists due to insufficient neutralization of header syntax in Roundcube Webmail's message disposition notification subject handling when constructing notification messages. A remote attacker can supply a crafted subject used in an MDN to insert unintended mail headers.
Affected software
Roundcube Webmail
Remediation
Install security update from vendor's website.
Roundcube Webmail - addressed in versions 1.6.21, 1.7.6