In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, responses from the CSS (Cascading Style Sheets) proxy were not validated, which may result in information disclosure or XSS (cross-site scripting) via MIME sniffing.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-2aba9ce8fc advisory.

    ## Version 1.7.5

    - Installer: Add possibility to detsroy the installer session/cookie
    - Enigma: Fix db_sync() never restoring keyring files (#10343)
    - Markasjunk: Skip messages whose %s/%h values start with '-' (#10344)
    - Password: Replace SQL query placeholders in a single pass (#10345)
    - Fix exit code of the healthcheck.sh script (#10337)
    - 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 Fedora 45 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-7002464a52 advisory.

    ## Version 1.7.5

    - Installer: Add possibility to detsroy the installer session/cookie
    - Enigma: Fix db_sync() never restoring keyring files (#10343)
    - Markasjunk: Skip messages whose %s/%h values start with '-' (#10344)
    - Password: Replace SQL query placeholders in a single pass (#10345)
    - Fix exit code of the healthcheck.sh script (#10337)
    - 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 openSUSE 16 host has a package installed that is affected by multiple vulnerabilities as referenced in the openSUSE-SU-2026:22195-1 advisory.

    Changes in roundcubemail:

    Update to 1.6.20:

      This is a security update to the version 1.6 of Roundcube Webmail.
      It provides fixes to recently reported security vulnerabilities:

      - Fix IMAP command injection via CRLF in _uid parameter of mail/headers and mail/viewsource action,     reported by Wahab NeoX K.
      - Fix bug where an alias login wasn't qualified by IMAP host, reported by Milan Hoppe.
      - Add a size limit to the CSS proxy content processing, reported by Milan Hoppe.
      - Fix SSRF filter (is_local_url()) bypass via NAT64 64:ff9b::/96, reported by dizconnect.
      - Fix remote content blocking bypass via SVG SMIL by attribute, reported by Milan Hoppe.
      - Fix remote content blocking bypass via CSS escapes in FuncIRI attributes (again), reported by Milan     Hoppe.
      - Fix passing potentally unsafe attachment content into ImageMagick on image resize, reported by Paulos     Yibelo
      - Fix mail header injection via the From display-name in the Bounce (resend) action, reported by Clay.
      - Fix mail header injection via References/In-Reply-To/Message-ID/From parameters, reported by Sunil     Tripathy.
      - Fix object injection primitive in rcube_session::unserialize() via !-prefixed session keys, reported     by Oli Z.
      - Fix ImageMagick resource limits bypass by GD fallback during thumbnail generation, reported by     GoldenSW.
      - Fix CSS scoping bypass in HTML messages using at-rules, reported by GoldenSW.
      - Fix bug where deprecated action aliases bypassed disabled_actions setting, reported by Squirt1e, Atum,     N0b0dy, and Gh0u1L5.
      - Fix IMAP command injection via CRLF in _flag parameter of mail/mark action, reported by Squirt1e,     Atum, N0b0dy, and Gh0u1L5.
      - Fix CSRF validation bypass in the mark-as-junk action, reported by Squirt1e, Atum, N0b0dy, and     Gh0u1L5.
      - Fix XSS issue in handling of password driver error responses, reported by Squirt1e, Atum, N0b0dy, and     Gh0u1L5.
      - Fix mail header injection via subject of a message forwarded as attachment, reported by Squirt1e,     Atum, N0b0dy, and Gh0u1L5.
      - Fix mail header injection via media type in an inline image data URI, reported by Squirt1e, Atum,     N0b0dy, and Gh0u1L5.
      - Fix bug where Password Modoboa driver could change password for another account, reported by Squirt1e,     Atum, N0b0dy, and Gh0u1L5.
      - Fix unsafe use of a login name in SquirrelMail import file path, reported by Squirt1e, Atum, N0b0dy,     and Gh0u1L5.

      This version is considered stable and we recommend to update all productive       installations of Roundcube with it. Please do backup your data before updating!

    Update to 1.6.19:

      This is a security update to the version 1.6 of Roundcube Webmail.
      It provides fixes to recently reported security vulnerabilities:

      - Fix CSS declaration smuggling via un-encoded ampersand emission, reported by Zach Hanley of     Horizon3.ai
      - Fix CSS property injection via body background attribute, reported by zenithhostingevan
      - Fix email header injection via bare CR in the subject field, reported by CVE-Hunter-Leo
      - Fix email header injection via C-escape \r in the recipient display name, reported by dogeshark       + Fix email header injection via identity's organization field, reported by dogeshark       + Fix zero-click stored XSS via TNEF MIME tag injection in the attachment URL, reported by nakko       + Fix XSS in the HTML editor using text/enriched part content, reported by Joshua Rogers       + Fix cross-user access in contact group membership (add/remove) in the SQL address book, reported by     Joshua Rogers       + Fix is_local_url() bypass via trailing-dot FQDN in stylesheet URL, reported by nept1337       + Fix remote content blocking bypass via CSS escapes in FuncIRI attributes, reported by neoxed       + Fix remote-content blocker bypass via SVG SMIL src animation       + Fix SSRF bypass in Roundcube CSS proxy via hexadecimal IPv6-mapped IPv4 addresses, reported by     faceless0x7 and Harish Annavisamy

      This version is considered stable and we recommend to update all productive       installations of Roundcube with it. Please do backup your data before updating!

    Update to 1.6.18 [boo#1275552]:

      + Password: Fix fatal error Class 'Zxcvbn' not found (#10274)       + Fix out-of-bounds string reads on truncated compressed-RTF in the TNEF decoder (#10269)       + Security: Add basic validation for content proxied by the css proxy [CVE-2026-74998] [boo#1275324]       + Security: Fix SSRF bypass via specific local address URLs using 100.64.0.0/10 and fe80::/10 nets     [CVE-2026-75006] [boo#1275319]       + Security: Fix SSRF filter bypass via various forms of nip.io/sslip.io hostnames evading is_local_url()     check [CVE-2026-75006] [boo#1275319]       + Security: Fix remote content blocking bypass via unclosed url() in a FuncIRI attribute     [CVE-2026-75003] [boo#1275320]       + Security: Fix LDAP filter injection via unescaped %u/%fu/%d substitution into the search_filter     [CVE-2026-75007] [boo#1275318]       + Security: Fix arbitrary Sieve script injection via a filter rule name bypassing     managesieve_disabled_actions [CVE-2026-75004] [boo#1275445]       + Security: Fix RCE via cmd_learn driver of markasjunk plugin [CVE-2026-74997] [boo#1275325]       + Security: Fix IMAP command injection via mail search and LITERAL+ byte-count desynchronization     [CVE-2026-75002] [boo#1275321]       + Security: Fix password's modoboa driver leak of an authentication token to a user-controlled host     [CVE-2026-75010] [boo#1275317]       + Security: Fix stored XSS in Add to address book action [CVE-2026-74999] [boo#1275323]       + Security: Fix HTML/CSS sanitization bypass via SVG animate by attribute [CVE-2026-75000] [boo#1275322]

    Update to 1.6.17:

      + Enigma: Support automatic public key lookup (import) using HKP v1 protocol (#5314)       + Enigma: Kolab WOAT Support (#8626)       + Security: Fix an infinite loop in TNEF (winmail.dat) decoder (#10193) [CVE-2026-62642] [boo#1271475]       + Security: Fix various vulnerabilities in the password plugin using session-injected username     [CVE-2026-62644] [boo#1271474]       + Security: Fix stored XSS via unescaped attachment MIME type on the attachment-validation warning page     [CVE-2026-54432] [boo#1271471]       + Security: Fix SSRF bypass via specific local address URLs - two new cases [CVE-2026-62643]     [boo#1271477]       + Security: Fix zero-click stored XSS in plain-text rendering [CVE-2026-54433] [boo#1271472]       + Security: Fix DoS via crafted compressed-RTF size in the TNEF (winmail.dat) file [CVE-2026-62641]     [boo#1271476]


    Additional references added to older update:  (bsc#1243915, CVE-2025-49113)

Tenable has extracted the preceding description block directly from the SUSE 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 web server is running Roundcube Webmail version 1.6.x prior to 1.6.18 or 1.7.x prior to 1.7.3. It is, therefore, affected by multiple vulnerabilities:

  - The cmd_learn driver of the markasjunk plugin is subject to remote code execution via crafted placeholder     replacement values. This issue only affects Roundcube instances using the markasjunk plugin with its cmd_learn     driver. (CVE-2026-74997)

  - Mail search and LITERAL+ byte-count desynchronization could lead to information disclosure or privilege     escalation via IMAP command injection. (CVE-2026-75002)

  - Responses from the CSS (Cascading Style Sheets) proxy were not validated, which may result in information     disclosure or XSS (cross-site scripting) via MIME sniffing. (CVE-2026-74998)

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-6479 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6479-1                   security@debian.org     https://www.debian.org/security/                     Salvatore Bonaccorso     August 30, 2026                       https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : roundcube     CVE ID         : CVE-2026-74997 CVE-2026-74998 CVE-2026-74999 CVE-2026-75000                      CVE-2026-75002 CVE-2026-75003 CVE-2026-75004 CVE-2026-75006                      CVE-2026-75007 CVE-2026-75010     Debian Bug     : 1144059

    Multiple vulnerabilities were discovered in roundcube, a skinnable AJAX     based webmail solution for IMAP servers, which could result in     cross-site scripting, SSRF bypass, information disclosure, privilege     escalation, denial of service or remote code execution.

    For the stable distribution (trixie), these problems have been fixed in     version 1.6.18+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 remote Debian 11 / 12 host has packages installed that are affected by multiple vulnerabilities as referenced in the dla-4760 advisory.

    -------------------------------------------------------------------------     Debian LTS Advisory DLA-4760-1                debian-lts@lists.debian.org     https://www.debian.org/lts/security/                       Guilhem Moulin     August 29, 2026                               https://wiki.debian.org/LTS
    -------------------------------------------------------------------------

    Package        : roundcube     Version        : 1.4.15+dfsg.1-1+deb11u11 1.6.5+dfsg-1+deb12u11     CVE ID         : CVE-2026-74997 CVE-2026-74998 CVE-2026-74999 CVE-2026-75000                      CVE-2026-75002 CVE-2026-75003 CVE-2026-75004 CVE-2026-75006                      CVE-2026-75007 CVE-2026-75010     Debian Bug     : 1144059

    Multiple vulnerabilities were discovered in Roundcube, a skinnable AJAX based     webmail solution for IMAP servers, which could result in cross-site scripting,     server-side request forgery, information disclosure, privilege escalation, IMAP     injection, account takeover, or remote code execution.

    CVE-2026-74997

        A remote code execution vulnerability was found in the cmd_learn learning         driver of the markasjunk plugin.  Placeholders such as %u (username), %l         (localpart) and %d (domainpart) were injected with insufficiently         sanitized/escaped values used within a `sh -c ''` shell construction,         thereby allowing remote code execution from the user used to run roundcube         (by default www-data).

        Only installations where 1/ the markasjunk plugin was enabled, and 2/         where the `$config['markasjunk_learning_driver']` setting was set to         `cmd_learn`, were affected by this vulnerability.  In particular, stock         installations were not affected since the plugin is not enabled by default.

    CVE-2026-74998

        Content proxied by the CSS proxy (which is used to retrieve remote style         sheets linked to in text/html emails) was found to be lacking basic         validation, which may result in information disclosure or XSS (cross-site         scripting) via MIME sniffing.

    CVE-2026-74999

        Paulos Yibelo discovered that the Add to address book action was subject         to stored XSS due to insufficient sanitization of error messages and         information popups.

    CVE-2026-75000

        Insufficient HTML/CSS sanitization may lead to remote image blocking bypass         or XSS via crafted SVG animate `by` attribute sent in malicious text/html         emails.

    CVE-2026-75002

        Zach Hanley discovered that mail search and RFC2088 IMAP4 LITERAL+         byte-count desynchronization may lead to IMAP command injection.

    CVE-2026-75003

        Milan Hoppe discovered that insufficient HTML/CSS sanitization may lead to         remote image blocking bypass or XSS via unclosed url() in a FuncIRI         attribute.

    CVE-2026-75004

        Milan Hoppe discovered that managesieve rule names were not sanitized,         thereby allowing arbitrary sieve injection and bypass of the         managesieve_disabled_actions restriction set by an administrator.

        This vulnerability only affects installations where the managesieve plugin         is enabled.  In particular, stock installations were not affected since the         plugin is not enabled by default.

    CVE-2026-75006

        Dmytro Ivanenko and Milan Hoppe discovered that that the CSS sanitization         fixes for CVE-2026-35540, CVE-2026-48843 and CVE-2026-62643 were         insufficient, allowing a malicious embedded stylesheet in a text/html email         to lead to SSRF or information disclosure.

    CVE-2026-75007

        Milan Hoppe discovered that the LDAP integration was subject to filter         injection via unescaped %u/%fu/%d substitution.

    CVE-2026-75010

        The modoba driver of the password plugin was found to be leaking an         authentication token, which may lead to account takeover.

        Only installations where 1/ the password plugin was enabled, and 2/         where the `$config['password_driver']` setting was set to `modoboa`,         were affected by this vulnerability.  In particular, stock installations         were not affected since the password plugin is not enabled by default.

    For Debian 11 bullseye, these problems have been fixed in version     1.4.15+dfsg.1-1+deb11u11.

    For Debian 12 bookworm, these problems have been fixed in version     1.6.5+dfsg-1+deb12u11.

    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 LTS security advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://wiki.debian.org/LTS     Attachment:
    signature.asc     Description: PGP signature

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.

  - In Roundcube Webmail before 1.6.18 and 1.7.x before 1.7.3, responses from the CSS (Cascading Style Sheets)     proxy were not validated, which may result in information disclosure or XSS (cross-site scripting) via     MIME sniffing. (CVE-2026-74998)

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

ID	Name	Product	Family	Type	Severity
376336	Fedora 44 : roundcubemail (2026-2aba9ce8fc)	Nessus	Fedora Local Security Checks	Local	high
376321	Fedora 45 : roundcubemail (2026-7002464a52)	Nessus	Fedora Local Security Checks	Local	high
374751	openSUSE 16 Security Update : roundcubemail (openSUSE-SU-2026:22195-1)	Nessus	SuSE Local Security Checks	Local	critical
342614	Roundcube Webmail 1.6.x < 1.6.18 / 1.7.x < 1.7.3 Multiple Vulnerabilities	Nessus	CGI abuses	Remote	critical
341608	Debian dsa-6479 : roundcube - security update	Nessus	Debian Local Security Checks	Local	critical
341564	Debian dla-4760 : roundcube - security update	Nessus	Debian Local Security Checks	Local	critical
337106	Linux Distros Unpatched Vulnerability : CVE-2026-74998	Nessus	Misc.	Local	high

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CVE-2026-74998

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