{"id":"CVE-2026-45125","summary":"MyBB: Email User CRLF injection","details":"MyBB is free and open source forum software. Prior to 1.8.40, the Email User controller does not sanitize sender names correctly, resulting in mail header injection. member.php?action=do_emailuser accepts the fromname HTTP parameter for guests or the stored username for authenticated users when the cansendemail group permission is enabled. When mail_handler is set to the default PHP mail value, the sender name is used without sanitization in Return-Path and Reply-To headers, allowing arbitrary headers to be injected with CRLF sequences. This issue is fixed in version 1.8.40.","aliases":["GHSA-f626-53q9-pqm9"],"modified":"2026-08-20T03:54:20.696090869Z","published":"2026-08-18T15:50:38.936Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45125.json","unresolved_ranges":[{"source":"AFFECTED_FIELD","extracted_events":[{"fixed":"1.8.40"}]}],"cna_assigner":"GitHub_M","cwe_ids":["CWE-93"]},"references":[{"type":"WEB","url":"https://github.com/mybb/mybb/releases/tag/mybb_1840"},{"type":"WEB","url":"https://mybb.com/versions/1.8.40"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/45xxx/CVE-2026-45125.json"},{"type":"ADVISORY","url":"https://github.com/mybb/mybb/security/advisories/GHSA-f626-53q9-pqm9"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-45125"},{"type":"FIX","url":"https://github.com/mybb/mybb/commit/5046c56b515d4593297a4f65b0c6ccb0b55baa01"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/mybb/mybb","events":[{"introduced":"0"},{"fixed":"5046c56b515d4593297a4f65b0c6ccb0b55baa01"},{"fixed":"e9942c6d19ac1709b3df7357cfb8810774c8d3ac"}],"database_specific":{"source":"REFERENCES"}}],"versions":["mybb_1840_build","mybb_1839","mybb_1839_build","mybb_1838","mybb_1838_build","mybb_1837","mybb_1837_build","mybb_1836","mybb_1835_build","mybb_1835","mybb_1834","mybb_1834_build","mybb_1833","mybb_1833_build","mybb_1832","mybb_1832_build","mybb_1831","mybb_1831_build","mybb_1829","mybb_1828","mybb_1828_build","mybb_1827_build","mybb_1827","mybb_1823_build","mybb_1823","mybb_1822","mybb_1822_build","mybb_1821pl1","mybb_1821","mybb_1821_build","mybb_1817_build","mybb_1817","mybb_1820","mybb_1820_build","mybb_1820-rc","mybb_1819","mybb_1818","mybb_1819_build","mybb_1818_build","mybb_1816","mybb_1816_build","mybb_1815","mybb_1815_build","mybb_1814","mybb_1813","mybb_1812","mybb_1811","mybb_1810","mybb_1809","mybb_1808","mybb_1807","mybb_1806","mybb_1805","mybb_1804","mybb_1800","mybb_1801"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-45125.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"}]}