Security Vulnerabilities
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 contains an object injection primitive in rcube_session::unserialize(). A session key prefixed with “!” was treated as having no value, and the reconstructed serialized string was emitted with a key but no corresponding value, desynchronizing the remainder of the input so that following session data was interpreted as a serialized value. This yields a PHP object injection primitive for an attacker able to influence stored session data. Upstream fixed this in the commit “Fix object injection primitive in rcube_session::unserialize() via “!”-prefixed session keys”, which rejects such keys.
CVSS Score
7.4
EPSS Score
0.004
Published
2026-10-22
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.
CVSS Score
5.0
EPSS Score
0.003
Published
2026-10-22
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a mail header injection vulnerability in the Bounce (resend) action. rcube_mime::decode_address_list() did not strip control characters from the decoded display name, so a received message whose From display-name carries CRLF sequences in an encoded word could inject arbitrary headers into the message emitted when the user bounces it. Upstream fixed this in the commit “Fix mail header injection via the From display-name in the Bounce (resend) action”.
CVSS Score
5.8
EPSS Score
0.003
Published
2026-10-22
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a remote content blocking bypass in the handling of FuncIRI attributes. rcube_washtml detected the CSS url() token with a pattern that enumerated only some of its escaped spellings, so values using other CSS escape sequences, for example \000075rl( or u\72 l(, were not recognized and remote content was loaded from an HTML message without the user's consent. Upstream fixed this in the commit “Fix remote content blocking bypass via CSS escapes in FuncIRI attributes (again)”, which resolves CSS escapes before matching and also inspects the `to`, `from` and `by` attributes.
CVSS Score
5.3
EPSS Score
0.004
Published
2026-10-22
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a CSS scoping bypass in HTML messages. rcube_utils::mod_css_styles() did not treat an at-rule prologue such as @layer a; as a selector boundary, and did not handle selectors beginning with ::, so selectors following an at-rule were left unscoped and applied to the whole Roundcube interface instead of being confined to the message body. This allows an HTML message to restyle application chrome for UI redressing and spoofing. Upstream fixed this in the commit “Fix CSS scoping bypass in HTML messages using at-rules”.
CVSS Score
6.5
EPSS Score
0.003
Published
2026-10-22
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 allows the ImageMagick resource limits to be bypassed during thumbnail generation. When rcube_image falls back to GD, the available-memory check was applied only on Windows, so on other platforms a crafted image with large dimensions was processed by GD without any resource limit and could exhaust server memory. Upstream fixed this in the commit “Fix ImageMagick resource limits bypass by GD fallback during thumbnail generation”, which applies the memory check on all platforms.
CVSS Score
3.7
EPSS Score
0.003
Published
2026-10-22
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 passes potentially unsafe content into ImageMagick when resizing images. SVG and EPS were accepted as valid image types for contact photo upload and conversion, and both formats can reference external resources and invoke ImageMagick delegates when processed. Upstream fixed this in the commit “Fix passing potentally unsafe attachment content into ImageMagick on image resize”, which removes svg and eps from the accepted types.
CVSS Score
8.3
EPSS Score
0.003
Published
2026-10-22
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().
CVSS Score
8.5
EPSS Score
0.004
Published
2026-10-22
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a mail header injection vulnerability when a message is forwarded as an attachment. The subject of the forwarded message was used verbatim to generate the attachment name, so a received message whose subject contains CRLF sequences could inject arbitrary MIME part headers into the outgoing message. Upstream fixed this in the commit “Fix mail header injection via subject of a message forwarded as attachment”, which collapses whitespace in the generated name.
CVSS Score
4.0
EPSS Score
0.004
Published
2026-10-22
Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by a cross-site scripting vulnerability in the password plugin. Error text returned by a password driver was concatenated into the message presented to the user without HTML escaping, so a backend able to influence that text, such as the DirectAdmin API, could inject script into the Roundcube interface. Upstream fixed this in the commit “Fix XSS issue in handling of password driver error responses”, which escapes the driver message before display.
CVSS Score
4.7
EPSS Score
0.003
Published
2026-10-22