CVE-2025-62786 Overview
CVE-2025-62786 is a heap-based out-of-bounds write vulnerability affecting Wazuh, a free and open source platform used for threat prevention, detection, and response. The vulnerability exists in the decode_win_permissions function, where a NULL byte can be written 2 bytes before the start of the buffer allocated to decoded_it. A compromised agent can potentially leverage this issue to perform remote code execution by sending a specially crafted message to the Wazuh manager.
Critical Impact
A compromised Wazuh agent can exploit this heap-based out-of-bounds write to potentially achieve remote code execution on the Wazuh manager, depending on heap allocator specifics.
Affected Products
- Wazuh versions prior to 4.10.2
Discovery Timeline
- 2025-10-29 - CVE-2025-62786 published to NVD
- 2025-11-03 - Last updated in NVD database
Technical Details for CVE-2025-62786
Vulnerability Analysis
This vulnerability is classified as CWE-124 (Buffer Underwrite), a specific form of memory corruption where data is written before the beginning of an allocated buffer. The flaw exists in the Windows permissions parser functionality within Wazuh's syscheck module. When processing specially crafted permission strings, the decode_win_permissions function fails to properly validate input boundaries before performing write operations.
The exploitation of this vulnerability requires network access with high attack complexity. An attacker must control or compromise a Wazuh agent and craft a malicious message that triggers the vulnerable code path. While the exploitability depends on the specifics of the respective heap allocator implementation, successful exploitation could lead to arbitrary code execution on the Wazuh manager server.
Root Cause
The root cause lies in insufficient input validation within the decode_win_permissions function in src/shared/syscheck_op.c. The parser does not validate the remaining length of the permission string before processing, allowing malformed inputs to cause the function to write outside the allocated buffer boundaries. Specifically, the code did not check whether there were at least 3 characters remaining (minimum size for the next permission) before attempting to parse the next permission entry.
Attack Vector
The attack is network-based and requires a compromised or malicious Wazuh agent. The attacker must:
- Gain control of a Wazuh agent or position themselves to send agent messages
- Craft a malicious message containing a specially formatted Windows permission string
- Send the crafted message to the Wazuh manager
- Trigger the decode_win_permissions function with insufficient remaining data after a pipe delimiter
- Cause an out-of-bounds write that could corrupt heap metadata or adjacent allocations
The security patch addresses this by adding bounds checking:
int perm_size = MAX_WIN_PERM_SIZE;
char *decoded_it = decoded_perm;
char *perm_it = raw_perm;
+ char *perm_end = perm_it + strlen(raw_perm);
while (perm_it = strchr(perm_it, '|'), perm_it) {
+ // Minimum size for the next permission
+ if (perm_end - perm_it < 3) {
+ goto error;
+ }
+
// Get the account/group name
base_it = ++perm_it;
if (perm_it = strchr(perm_it, ','), !perm_it) {
Source: GitHub Commit Reference
Detection Methods for CVE-2025-62786
Indicators of Compromise
- Unexpected crashes or segmentation faults in the Wazuh manager process
- Malformed Windows permission strings in agent-to-manager communication logs
- Anomalous agent messages containing truncated or malformed syscheck data
- Evidence of heap corruption in Wazuh manager core dumps
Detection Strategies
- Monitor Wazuh manager logs for parsing errors related to Windows permissions
- Deploy memory protection tools (ASAN, Valgrind) in testing environments to detect heap corruption
- Implement network monitoring for anomalous agent-to-manager traffic patterns
- Review agent authentication logs for suspicious or compromised agent connections
Monitoring Recommendations
- Enable verbose logging on Wazuh manager to capture detailed syscheck processing events
- Configure alerting for Wazuh manager process crashes or unexpected restarts
- Monitor agent registration and authentication events for unauthorized agents
- Implement network segmentation to limit agent-to-manager communication paths
How to Mitigate CVE-2025-62786
Immediate Actions Required
- Upgrade Wazuh to version 4.10.2 or later immediately
- Review and verify the integrity of all registered Wazuh agents
- Monitor Wazuh manager systems for signs of compromise or exploitation attempts
- Implement network access controls to restrict agent-to-manager communication
Patch Information
Wazuh has released version 4.10.2 which addresses this vulnerability. The fix adds proper bounds checking in the decode_win_permissions function to ensure that sufficient data remains before attempting to parse the next permission entry. The patch commit 2257d7998aaff34263169d16f4afc491564a771c introduces validation that verifies at least 3 characters remain after each pipe delimiter before proceeding with parsing.
For detailed patch information, refer to the GitHub Security Advisory GHSA-2c8r-p6r5-xxmr.
Workarounds
- Implement strict network segmentation between Wazuh agents and manager
- Monitor and audit all agent connections for suspicious behavior
- Deploy additional network security controls to filter malformed agent messages
- Consider temporarily isolating untrusted or potentially compromised agents until patching is complete
# Verify Wazuh version after upgrade
/var/ossec/bin/wazuh-control info | grep VERSION
# Check Wazuh manager service status
systemctl status wazuh-manager
# Review agent connections
/var/ossec/bin/agent_control -l
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
