Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a mail header injection vulnerability. rcmail_sendmail::extract_inline_images() used the media type taken from an inline image data URI without validating it, so a remote…

Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a mail header injection vulnerability. rcmail_sendmail::extract_inline_images() used the media type taken from an inline image data URI without validating it, so a remote authenticated attacker could inject arbitrary MIME part headers into the outgoing message by placing CRLF sequences in that media type. Upstream fixed this in the commit “Fix mail header injection via media type in an inline image data URI”, which validates the media type with rcube_mime::is_mimetype_valid().

Source published

22 Oct 2026 01:17:45 UTC

Source modified

26 Oct 2026 16:46:46 UTC

Observed here

26 Oct 2026 17:35:31 UTC

Source terms

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CVSS 3.1 · 8.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:H/A:N