{"apiVersion":"1.0","identifier":"CVE-2026-45123","description":"MyBB is free and open source forum software. Prior to 1.8.40, the remote requests feature does not correctly handle IPv6 addresses, resulting in a server-side request forgery vulnerability. The default disallowed remote hosts list does not include IPv6 addresses. Verification in fetch_remote_file() fails open when get_ip_by_hostname() returns no result because that function does not return IPv6 results, allowing a crafted remote target to bypass the host restriction. The uniquely identifying implementation details include fail-open verification, and inc/functions.php. This issue is fixed in version 1.8.40.","publishedAt":"2026-08-18T16:17:07","lastModifiedAt":"2026-08-18T19:16:50","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-45123","cvssScore":4.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N","epssProbability":0.00269,"riskScore":0.44,"affectedProduct":"MyBB","affectedVersions":"<1.8.40","vulnerabilityType":"Web app","operatingSystems":[],"links":{"self":"https://www.redsauce.net/api/cves/CVE-2026-45123","webPages":{"es":"https://www.redsauce.net/es/cves/CVE-2026-45123","en":"https://www.redsauce.net/en/cves/CVE-2026-45123","fr":"https://www.redsauce.net/fr/cves/CVE-2026-45123","pt":"https://www.redsauce.net/pt/cves/CVE-2026-45123","de":"https://www.redsauce.net/de/cves/CVE-2026-45123","sk":"https://www.redsauce.net/sk/cves/CVE-2026-45123","el":"https://www.redsauce.net/el/cves/CVE-2026-45123"},"source":"https://nvd.nist.gov/vuln/detail/CVE-2026-45123"}}