The K2 article gallery upload path accepts a zip/tar archive, extracts it under `/media/k2/galleries/<id>/`, and only renames image files (gif/jpg/jpeg/png/webp) to safe names — non-image files (including `.php`) are extracted as-is and remain executable via direct HTTP access.

A Joomla user with K2 "create item" rights (Author tier by default) can submit an article whose `embedVideo` POST field contains a raw `<script>` tag; K2 stores it verbatim and renders it unescaped to any visitor of the article page.

The K2 frontend `item.checkin` task accepts an unauthenticated `sigProFolder` query parameter and uses it directly to address a `JFolder::delete()` call under `/media/k2/galleries/`

The K2 frontend article-attachment upload path accepts files whose extension is `.php`, and Apache's standard mod_php matches `\.php$` and executes them under the K2 web user. A K2 Author can upload a `shell.php`, then fetch `/media/k2/attachments/shell.php` and execute arbitrary PHP code in the web server's context.

The K2 frontend article-save handler accepts an `attachment[N][existing]` POST field that is concatenated with `JPATH_SITE/` and passed to `JFile::copy()`. `JPath::clean` does NOT strip `..`, and there is no allow-list of source paths. An Author can therefore copy `configuration.php` (or any other file readable by the web user — including `../../../etc/passwd`) into `/media/k2/attachments/`, then retrieve the contents via the K2 attachment-download endpoint.

K2 ≤ 2.26 renders the `#__k2_users.image` column directly into HTML `src` attributes via two distinct templates, in both cases without HTML escaping.

K2 ≤ 2.24 contains a mass-assignment defect in the K2 system user plugin `plg_user_k2`. A Registered Joomla user, by including the field `K2UserForm=1` in a standard `com_users` `profile.save` POST, can write arbitrary values into the `notes`, `image`, and `plugins` columns of their own row in the `#__k2_users` table — none of which are exposed by the K2 frontend profile-edit form.

Phicomm k2 v22.6.529.216 was discovered to contain a command injection vulnerability via the function luci.sys.call.

Phicomm K2 v22.6.534.263 was discovered to store the root and admin passwords in plaintext.

Phicomm K2 v22.6.534.263 was discovered to contain a command injection vulnerability via the autoUpTime parameter in the automatic upgrade function.

Phicomm K2G v22.6.3.20 was discovered to contain a command injection vulnerability via the autoUpTime parameter in the automatic upgrade function.

Phicomm K2G v22.6.3.20 was discovered to store the root and admin passwords in plaintext.

A null byte interaction error has been discovered in the code that the telnetd_startup daemon uses to construct a pair of ephemeral passwords that allow a user to spawn a telnet service on the router, and to ensure that the telnet service persists upon reboot. By means of a crafted exchange of UDP packets, an unauthenticated attacker on the local network can leverage this null byte interaction error in such a way as to make those ephemeral passwords predictable (with 1-in-94 odds). Since the attacker must manipulate data processed by the OpenSSL function RSA_public_decrypt(), successful exploitation of this vulnerability depends on the use of an unpadded RSA cipher (CVE-2022-25218).

Improper physical access control and use of hard-coded credentials in /etc/passwd permits an attacker with physical access to obtain a root shell via an unprotected UART port on the device. The same port exposes an unauthenticated Das U-Boot BIOS shell.

Improper access control on the LocalMACConfig.asp interface allows an unauthenticated remote attacker to add (or remove) client MAC addresses to (or from) a list of banned hosts. Clients with those MAC addresses are then prevented from accessing either the WAN or the router itself.

The use of the RSA algorithm without OAEP, or any other padding scheme, in telnetd_startup, allows an unauthenticated attacker on the local area network to achieve a significant degree of control over the "plaintext" to which an arbitrary blob of ciphertext will be decrypted by OpenSSL's RSA_public_decrypt() function. This weakness allows the attacker to manipulate the various iterations of the telnetd startup state machine and eventually obtain a root shell on the device, by means of an exchange of crafted UDP packets. In all versions but K2 22.5.9.163 and K3C 32.1.15.93 a successful attack also requires the exploitation of a null-byte interaction error (CVE-2022-25219).

Use of a hard-coded cryptographic key pair by the telnetd_startup service allows an attacker on the local area network to obtain a root shell on the device over telnet. The builds of telnetd_startup included in the version 22.5.9.163 of the K2 firmware, and version 32.1.15.93 of the K3C firmware (possibly amongst many other releases) included both the private and public RSA keys. The remaining versions cited here redacted the private key, but left the public key unchanged. An attacker in possession of the leaked private key may, through a scripted exchange of UDP packets, instruct telnetd_startup to spawn an unauthenticated telnet shell as root, by means of which they can then obtain complete control of the device. A consequence of the limited availablility of firmware images for testing is that models and versions not listed here may share this vulnerability.

Improper access control on the LocalClientList.asp interface allows an unauthenticated remote attacker to obtain sensitive information concerning devices on the local area network, including IP and MAC addresses. Improper access control on the wirelesssetup.asp interface allows an unauthenticated remote attacker to obtain the WPA passphrases for the 2.4GHz and 5.0GHz wireless networks. This is particularly dangerous given that the K2G setup wizard presents the user with the option of using the same password for the 2.4Ghz network and the administrative interface, by clicking a checkbox. When Remote Managment is enabled, these endpoints are exposed to the WAN.

class.upload.php in verot.net class.upload through 1.0.3 and 2.x through 2.0.4, as used in the K2 extension for Joomla! and other products, omits .pht from the set of dangerous file extensions, a similar issue to CVE-2019-19576.

class.upload.php in verot.net class.upload before 1.0.3 and 2.x before 2.0.4, as used in the K2 extension for Joomla! and other products, omits .phar from the set of dangerous file extensions.

The K2 component 2.8.0 for Joomla! has Incorrect Access Control with directory traversal, allowing an attacker to download arbitrary files, as demonstrated by a view=media&task=connector&cmd=file&target=l1_../configuration.php&download=1 request. The specific pathname ../configuration.php should be base64 encoded for a valid attack. NOTE: the vendor disputes this issue because only files under the media-manager path can be downloaded, and the documentation indicates that sensitive information does not belong there. Nonetheless, 2.8.1 has additional blocking of .php downloads