An issue was discovered in OSSEC 3.6.0. An uncontrolled recursion vulnerability in os_xml.c occurs when a large number of opening and closing XML tags is used. Because recursion is used in _ReadElem without restriction, an attacker can trigger a segmentation fault once unmapped memory is reached.

In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulnerable to a denial of service (NULL pointer dereference) via crafted messages written directly to the analysisd UNIX domain socket by a local user.

In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulnerable to a use-after-free during processing of syscheck formatted msgs (received from authenticated remote agents and delivered to the analysisd processing queue by ossec-remoted).

In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulnerable to path traversal (with write access) via crafted syscheck messages written directly to the analysisd UNIX domain socket by a local user.

In OSSEC-HIDS 2.7 through 3.5.0, the OS_CleanMSG function in ossec-analysisd doesn't remove or encode terminal control characters or newlines from processed log messages. In many cases, those characters are later logged. Because newlines (\n) are permitted in messages processed by ossec-analysisd, it may be possible to inject nested events into the ossec log. Use of terminal control characters may allow obfuscating events or executing commands when viewed through vulnerable terminal emulators. This may be an unauthenticated remote attack for certain types and origins of logged data.

In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulnerable to a use-after-free during processing of ossec-alert formatted msgs (received from authenticated remote agents and delivered to the analysisd processing queue by ossec-remoted).

In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulnerable to an off-by-one heap-based buffer overflow during the cleaning of crafted syslog msgs (received from authenticated remote agents and delivered to the analysisd processing queue by ossec-remoted).

In OSSEC-HIDS 2.7 through 3.5.0, the server component responsible for log analysis (ossec-analysisd) is vulnerable to a heap-based buffer overflow in the rootcheck decoder component via an authenticated client.

The agent in OSSEC through 3.1.0 on Windows allows local users to gain NT AUTHORITY\SYSTEM access via Directory Traversal by leveraging full access to the associated OSSEC server.

syscheck/seechanges.c in OSSEC 2.7 through 2.8.1 on NIX systems allows local users to execute arbitrary code as root.

Cross-site scripting (XSS) vulnerability in site/search.php in OSSEC Web UI before 0.9 allows remote attackers to inject arbitrary web script or HTML by leveraging an unanchored regex.

host-deny.sh in OSSEC before 2.8.1 writes to temporary files with predictable filenames without verifying ownership, which allows local users to modify access restrictions in hosts.deny and gain root privileges by creating the temporary files before automatic IP blocking is performed.