CVE-2026-41499: wazuh Buffer Underflow

Vulnerability summary

CVE-2026-41499 is a medium (CVSS 6.5) Buffer Underflow vulnerability in wazuh. EPSS estimates a 0.45% chance of exploitation in the next 30 days, higher than 37.6% of scored vulnerabilities.

Timeline

1. 29-04-2026
   PublishedVulnerability first disclosed.
2. 29-04-2026
   Last modifiedVulnerability information updated.

Description

Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 4.0.0 to before version 4.14.4, multiple heap-based out-of-bounds WRITE vulnerabilities exist in parse_uname_string() (remoted_op.c). This function processes OS identification data from agents and contains a dangerous code pattern that appears in 4 locations within the same function: writing to strlen(ptr) - 1 without checking for empty strings. When the string is empty, strlen() returns 0, and 0 - 1 wraps to SIZE_MAX due to unsigned integer underflow. Due to pointer arithmetic wrapping, SIZE_MAX effectively becomes -1, causing a write exactly 1 byte before the allocated buffer. This corrupts heap metadata (e.g., the chunk size field in glibc malloc), leading to heap corruption. This issue has been patched in version 4.14.4.

• CWE-124Buffer Underwrite ('Buffer Underflow')The product writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer.
• CWE-191Integer Underflow (Wrap or Wraparound)The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.