Horde IMP's AppleDouble MIME viewer writes an attacker-controlled attachment name into an HTML status block without escaping it. In lib/Mime/Viewer/Appledouble.php, IMPrender() obtains the name of the data part with IMPContents::getPartName(), which returns the MIME part's own name parameter as supplied by the message, and passes it through sprintf into the text of an IMPMimeStatus object. IMPMimeStatus::toString() concatenates each text entry directly into the surrounding table markup, so the value reaches the rendered page verbatim. A message crafted as multipart/appledouble whose data part carries markup in its name parameter therefore executes script in the context of any user who views it, and the payload persists in the mailbox. Exploitation requires no account on the target system, only the ability to send mail to a user. Version 7.2.0 escapes the value with htmlspecialchars(). The researcher additionally chains this flaw with the arbitrary file read of CVE-2026-58451, and reports that script running in an administrator's session can reach an application code-execution path.

Horde Virtual File System (VFS) API before 3.0.1 contains an OS command injection vulnerability in the HordeVfsSmb driver where the escapeShellCommand() method fails to sanitize command substitution sequences, allowing authenticated attackers to inject arbitrary shell commands through user-controlled filenames. Attackers can supply malicious filenames containing unescaped command substitution payloads through operations such as file upload, folder creation, rename, or deletion, which are interpolated into a double-quoted shell context and executed via procopen() through /bin/sh -c before smbclient runs, resulting in arbitrary command execution on the underlying system.

Horde IMP before 7.0.1 contains a path traversal vulnerability in lib/Compose.php that allows authenticated attackers to read arbitrary files from the server filesystem by embedding traversal sequences after a CKEditor path prefix in img src URLs. Attackers can bypass the stripos() prefix validation by appending sequences such as traversal segments after the matching prefix, causing filegetcontents() to read sensitive files whose contents are then exfiltrated as MIME parts in outgoing email; unauthenticated exploitation is also achievable via CSRF against an active authenticated session.

Horde Groupware v5.2.22 has a user enumeration vulnerability that allows an unauthenticated attacker to determine the existence of valid accounts on the system. To exploit the vulnerability, an HTTP request must be sent to ‘/imp/attachment.php’ including the parameters ‘id’ and ‘u’. If the specified user exists, the server will return the download of an empty file; if it does not exist, no download will be initiated, which unequivocally reveals the validity of the user.

Horde IMP through 6.2.27, as used with Horde Application Framework through 5.2.23, allows XSS that leads to account takeover via a crafted text/html e-mail message with an onerror attribute (that may use base64-encoded JavaScript code), as exploited in the wild in March 2025.

Horde Groupware Webmail Edition through 5.2.22 allows a reflection injection attack through which an attacker can instantiate a driver class. This then leads to arbitrary deserialization of PHP objects.

lib/Horde/Mime/Viewer/Ooo.php in Horde MimeViewer before 2.2.4 allows XSS via an OpenOffice document, leading to account takeover in Horde Groupware Webmail Edition. This occurs after XSLT rendering.

An XSS issue was discovered in Horde Groupware Webmail Edition through 5.2.22 (where the HordeTextFilter library before 2.3.7 is used). The attacker can send a plain text e-mail message, with JavaScript encoded as a link or email that is mishandled by preProcess in Text2html.php, because bespoke use of \x00\x00\x00 and \x01\x01\x01 interferes with XSS defenses.

Gollem before 3.0.13, as used in Horde Groupware Webmail Edition 5.2.22 and other products, is affected by a reflected Cross-Site Scripting (XSS) vulnerability via the HTTP GET dir parameter in the browser functionality, affecting breadcrumb output. An attacker can obtain access to a victim's webmail account by making them visit a malicious URL.

The image view functionality in Horde Groupware Webmail Edition before 5.2.22 is affected by a stored Cross-Site Scripting (XSS) vulnerability via an SVG image upload containing a JavaScript payload. An attacker can obtain access to a victim's webmail account by making them visit a malicious URL.

This vulnerability allows remote attackers to create arbitrary files on affected installations of Horde Groupware Webmail Edition 5.2.22. Authentication is required to exploit this vulnerability. The specific flaw exists within add.php. The issue results from the lack of proper validation of user-supplied data, which can allow the upload of arbitrary files. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the www-data user. Was ZDI-CAN-10125.

This vulnerability allows remote attackers to execute local PHP files on affected installations of Horde Groupware Webmail Edition 5.2.22. Authentication is required to exploit this vulnerability. The specific flaw exists within edit.php. When parsing the params[template] parameter, the process does not properly validate a user-supplied path prior to using it in file operations. An attacker can leverage this in conjunction with other vulnerabilities to execute code in the context of the www-data user. Was ZDI-CAN-10469.

Horde Groupware Webmail Edition 5.2.22 allows injection of arbitrary PHP code via CSV data, leading to remote code execution.

Multiple CSRF issues in Horde Groupware Webmail Edition 5.1.2 and earlier in basic.php.

Horde Groupware Web mail 5.1.2 has CSRF with requests to change permissions

Horde Groupware Webmail Edition has CSRF and XSS when saving search as a virtual address book

Horde Trean, as used in Horde Groupware Webmail Edition through 5.2.22 and other products, allows CSRF, as demonstrated by the treanBookmarkTags parameter to the trean/ URI on a webmail server. NOTE: treanBookmarkTags could, for example, be a stored XSS payload.

Horde Groupware Webmail Edition through 5.2.22 allows XSS via an admin/user.php?form=updatef&username= or admin/user.php?form=removef&username= or admin/config/diff.php?app= URI.

Remote code execution was discovered in Horde Groupware Webmail 5.2.22 and 5.2.17. Horde/Form/Type.php contains a vulnerable class that handles image upload in forms. When the HordeFormTypeimage method onSubmit() is called on uploads, it invokes the functions getImage() and getUpload(), which uses unsanitized user input as a path to save the image. The unsanitized POST parameter object[photo][img][file] is saved in the $upload[img][file] PHP variable, allowing an attacker to manipulate the $tmpfile passed to moveuploadedfile() to save the uploaded file. By setting the parameter to (for example) ../usr/share/horde/static/bd.php, one can write a PHP backdoor inside the web root. The static/ destination folder is a good candidate to drop the backdoor because it is always writable in Horde installations. (The unsanitized POST parameter went probably unnoticed because it's never submitted by the forms, which default to securely using a random path.)

The S/MIME specification allows a Cipher Block Chaining (CBC) malleability-gadget attack that can indirectly lead to plaintext exfiltration, aka EFAIL.

DISPUTED The OpenPGP specification allows a Cipher Feedback Mode (CFB) malleability-gadget attack that can indirectly lead to plaintext exfiltration, aka EFAIL. NOTE: third parties report that this is a problem in applications that mishandle the Modification Detection Code (MDC) feature or accept an obsolete packet type, not a problem in the OpenPGP specification.

In Horde Groupware 5.2.19, there is XSS via the Name field during creation of a new Resource. This can be leveraged for remote code execution after compromising an administrator account, because the CVE-2015-7984 CSRF protection mechanism can then be bypassed.

In Horde Groupware 5.2.19-5.2.22, there is XSS via the URL field in a "Calendar -> New Event" action.

In Horde Groupware 5.2.19 and 5.2.21, there is XSS via the Color field in a Create Task List action.

The File Manager (gollem) module 3.0.11 in Horde Groupware 5.2.21 allows remote attackers to bypass Horde authentication for file downloads via a crafted fn parameter that corresponds to the exact filename.

A Remote Code Execution vulnerability has been found in the HordeImage library when using the "Im" backend that utilizes ImageMagick's "convert" utility. It's not exploitable through any Horde application, because the code path to the vulnerability is not used by any Horde code. Custom applications using the HordeImage library might be affected. This vulnerability affects all versions of HordeImage from 2.0.0 to 2.5.1, and is fixed in 2.5.2. The problem is missing input validation of the index field in raw() during construction of an ImageMagick command line.

Denial of Service was found in HordeImage 2.x before 2.5.0 via a crafted URL to the "Null" image driver.

Remote Code Execution was found in HordeImage 2.x before 2.5.0 via a crafted GET request. Exploitation requires authentication.

In HordeCrypt before 2.7.6, as used in Horde Groupware Webmail Edition 5.x through 5.2.17, OS Command Injection can occur if the user has PGP features enabled in the user's preferences, and has enabled the "Should PGP signed messages be automatically verified when viewed?" preference. To exploit this vulnerability, an attacker can send a PGP signed email (that is maliciously crafted) to the Horde user, who then must either view or preview it.

In HordeCrypt before 2.7.6, as used in Horde Groupware Webmail Edition through 5.2.17, OS Command Injection can occur if the attacker is an authenticated Horde Webmail user, has PGP features enabled in their preferences, and attempts to encrypt an email addressed to a maliciously crafted email address.