Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by an IMAP command injection vulnerability. A remote authenticated attacker can exploit this via CRLF sequences injected into the _flag parameter of the mail/mark action to execute arbitrary IMAP commands. Upstream fixed this in the commit “Fix IMAP command injection via CRLF in `_flag` parameter of mail/mark action”, which rejects flags containing control, whitespace and IMAP-special characters.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-db7e033531 advisory.

    ## Version 1.6.20

    - Security: Fix IMAP command injection via CRLF in `_uid` parameter of mail/headers and mail/viewsource     action
    - Security: Fix bug where an alias login wasn't qualified by IMAP host
    - Security: Add a size limit to the CSS proxy content processing
    - Security: Fix SSRF filter (is_local_url()) bypass via NAT64 64:ff9b::/96
    - Security: Fix remote content blocking bypass via SVG SMIL `by` attribute
    - Security: Fix remote content blocking bypass via CSS escapes in FuncIRI attributes (again)
    - Security: Fix passing potentally unsafe attachment content into ImageMagick on image resize
    - Security: Fix mail header injection via the From display-name in the Bounce (resend) action
    - Security: Fix mail header injection via References/In-Reply-To/Message-ID/From parameters
    - Security: Fix object injection primitive in rcube_session::unserialize() via !-prefixed session keys
    - Security: Fix ImageMagick resource limits bypass by GD fallback during thumbnail generation
    - Security: Fix CSS scoping bypass in HTML messages using at-rules
    - Security: Fix bug where deprecated action aliases bypassed `disabled_actions` setting
    - Security: Fix IMAP command injection via CRLF in `_flag` parameter of mail/mark action
    - Security: Fix CSRF validation bypass in the mark-as-junk action
    - Security: Fix XSS issue in handling of password driver error responses
    - Security: Fix mail header injection via subject of a message forwarded as attachment
    - Security: Fix mail header injection via media type in an inline image data URI
    - Security: Fix bug where Password Modoboa driver could change password for another account
    - Security: Fix unsafe use of a login name in SquirrelMail import file path



Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6579 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6579-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     October 23, 2026                      https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : roundcube     CVE ID         : CVE-2026-113386 CVE-2026-114714 CVE-2026-114715 CVE-2026-114716                      CVE-2026-114717 CVE-2026-114718 CVE-2026-114719 CVE-2026-114720                      CVE-2026-114721 CVE-2026-114722 CVE-2026-114723 CVE-2026-114724                      CVE-2026-114725 CVE-2026-114726 CVE-2026-114727 CVE-2026-114728                      CVE-2026-114729 CVE-2026-114730 CVE-2026-114731 CVE-2026-114732     Debian Bug     : 1151279

    Multiple vulnerabilities were discovered in roundcube, a skinnable AJAX     based webmail solution for IMAP servers, which could result in IMAP     command injection, cross-site scripting, SSRF bypass, email header     injection, css property injection, remote content blocking bypass,     information disclosure or privilege escalation.

    For the stable distribution (trixie), these problems have been fixed in     version 1.6.20+dfsg-0+deb13u1.

    We recommend that you upgrade your roundcube packages.

    For the detailed security status of roundcube please refer to its     security tracker page at:
    https://security-tracker.debian.org/tracker/roundcube

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - Roundcube Webmail before 1.6.20 and 1.7.x before 1.7.5 is affected by an IMAP command injection     vulnerability. A remote authenticated attacker can exploit this via CRLF sequences injected into the _flag     parameter of the mail/mark action to execute arbitrary IMAP commands. Upstream fixed this in the commit     Fix IMAP command injection via CRLF in `_flag` parameter of mail/mark action, which rejects flags     containing control, whitespace and IMAP-special characters. (CVE-2026-114720)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
376324	Fedora 43 : roundcubemail (2026-db7e033531)	Nessus	Fedora Local Security Checks	Local	high
371198	Debian dsa-6579 : roundcube - security update	Nessus	Debian Local Security Checks	Local	high
370538	Linux Distros Unpatched Vulnerability : CVE-2026-114720	Nessus	Misc.	Local	high

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CVE-2026-114720

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