Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a mail header injection vulnerability. rcmail_sendmail stripped newline characters only from the Subject and Organization headers, leaving other header values taken from …

Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a mail header injection vulnerability. rcmail_sendmail stripped newline characters only from the Subject and Organization headers, leaving other header values taken from request parameters unsanitized, so a remote authenticated attacker could inject arbitrary headers into an outgoing message via the References, In-Reply-To, Message-ID and From parameters. Upstream fixed this in the commit “Fix mail header injection via References/In-Reply-To/Message-ID/From parameters”, which normalizes whitespace in every string header value.

Source published

22 Oct 2026 01:52:10 UTC

Source modified

22 Oct 2026 01:52:10 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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CVSS 3.1 · 5.0 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:L/A:N