{"id":"CVE-2026-26204","aliases":["EUVD-2026-26259","GHSA-j4c7-hwjw-8857"],"status":"published","title":"Wazuh: Heap-based NULL WRITE Buffer Underflow in GetAlertData","description":"Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 1.0.0 to before version 4.14.4, a heap-based out-of-bounds WRITE occurs in GetAlertData, resulting in writing a NULL byte exactly 1 byte before the start of the buffer allocated by strdup. Due to unsigned integer underflow and pointer arithmetic wrapping, the write lands at offset -1 from the buffer, corrupting heap metadata. A malicious actor can potentially leverage this issue through a compromised agent to cause denial of service or heap corruption by injecting a specially crafted alert into the alerts log file monitored by wazuh-logcollector. This issue has been patched in version 4.14.4.","severity":{"version":"3.1","score":4.4,"vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-12","score":0.00169,"percentile":0.06357,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-124","CWE-191"],"published":"2026-04-29T17:43:44Z","modified":"2026-11-11T21:10:00Z","products":[{"vendor":"wazuh","product":"wazuh"}],"references":[{"url":"https://github.com/wazuh/wazuh/security/advisories/GHSA-j4c7-hwjw-8857","tags":["x_refsource_CONFIRM","exploit","Exploit","Vendor Advisory","advisory"]},{"url":"https://github.com/wazuh/wazuh/releases/tag/v4.14.4","tags":["x_refsource_MISC","Release Notes","web"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26204.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-26204","tags":["advisory"]}],"sources":{"cve":[{"id":"CVE-2026-26204","title":"Wazuh: Heap-based NULL WRITE Buffer Underflow in GetAlertData","description":"Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 1.0.0 to before version 4.14.4, a heap-based out-of-bounds WRITE occurs in GetAlertData, resulting in writing a NULL byte exactly 1 byte before the start of the buffer allocated by strdup. Due to unsigned integer underflow and pointer arithmetic wrapping, the write lands at offset -1 from the buffer, corrupting heap metadata. A malicious actor can potentially leverage this issue through a compromised agent to cause denial of service or heap corruption by injecting a specially crafted alert into the alerts log file monitored by wazuh-logcollector. This issue has been patched in version 4.14.4.","status":"published","published":"2026-04-29T17:43:44.911Z","modified":"2026-04-30T12:48:18.639Z","cvss":[{"version":"3.1","score":4.4,"vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"cna"}],"cwes":["CWE-124","CWE-191"],"updated_at":"2026-11-02T13:38:20.971157Z"}],"euvd":[{"id":"EUVD-2026-26259","description":"Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 1.0.0 to before version 4.14.4, a heap-based out-of-bounds WRITE occurs in GetAlertData, resulting in writing a NULL byte exactly 1 byte before the start of the buffer allocated by strdup. Due to unsigned integer underflow and pointer arithmetic wrapping, the write lands at offset -1 from the buffer, corrupting heap metadata. A malicious actor can potentially leverage this issue through a compromised agent to cause denial of service or heap corruption by injecting a specially crafted alert into the alerts log file monitored by wazuh-logcollector. This issue has been patched in version 4.14.4.","status":"published","published":"2026-04-29T17:43:44Z","modified":"2026-04-30T12:48:18Z","cvss":[{"version":"3.1","score":4.4,"vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"updated_at":"2026-11-02T19:05:19.116327Z"}],"nvd":[{"id":"CVE-2026-26204","description":"Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 1.0.0 to before version 4.14.4, a heap-based out-of-bounds WRITE occurs in GetAlertData, resulting in writing a NULL byte exactly 1 byte before the start of the buffer allocated by strdup. Due to unsigned integer underflow and pointer arithmetic wrapping, the write lands at offset -1 from the buffer, corrupting heap metadata. A malicious actor can potentially leverage this issue through a compromised agent to cause denial of service or heap corruption by injecting a specially crafted alert into the alerts log file monitored by wazuh-logcollector. This issue has been patched in version 4.14.4.","status":"published","published":"2026-04-29T18:16:04.82Z","modified":"2026-11-11T21:10:00.2Z","cvss":[{"version":"3.1","score":4.4,"vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.5,"vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","level":"medium","assessor":"primary"}],"cwes":["CWE-124","CWE-191"],"updated_at":"2026-11-11T23:26:36.997374Z"}],"osv":[{"id":"CVE-2026-26204","title":"Wazuh: Heap-based NULL WRITE Buffer Underflow in GetAlertData","description":"Wazuh is a free and open source platform used for threat prevention, detection, and response. From version 1.0.0 to before version 4.14.4, a heap-based out-of-bounds WRITE occurs in GetAlertData, resulting in writing a NULL byte exactly 1 byte before the start of the buffer allocated by strdup. Due to unsigned integer underflow and pointer arithmetic wrapping, the write lands at offset -1 from the buffer, corrupting heap metadata. A malicious actor can potentially leverage this issue through a compromised agent to cause denial of service or heap corruption by injecting a specially crafted alert into the alerts log file monitored by wazuh-logcollector. This issue has been patched in version 4.14.4.","status":"published","published":"2026-04-29T17:43:44.911Z","modified":"2026-10-28T02:30:21.653693296Z","cvss":[{"version":"3.1","score":4.4,"vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H","level":"medium"}],"cwes":["CWE-124","CWE-191"],"updated_at":"2026-11-02T15:44:59.80315Z"}]}}