{"affected":[{"conditional":false,"product":"mastodon","source":"NVD","vendor":"joinmastodon","versions":[{"lessThan":"4.3.22","status":"affected","version":"*","versionType":"custom"}]},{"conditional":false,"product":"mastodon","source":"NVD","vendor":"joinmastodon","versions":[{"greaterThanOrEqual":"4.4.0","lessThan":"4.4.16","status":"affected","version":"*","versionType":"custom"}]},{"conditional":false,"product":"mastodon","source":"NVD","vendor":"joinmastodon","versions":[{"greaterThanOrEqual":"4.5.0","lessThan":"4.5.9","status":"affected","version":"*","versionType":"custom"}]}],"cpeConfigurations":[{"negate":false,"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*","versionEndExcluding":"4.3.22","vulnerable":true},{"criteria":"cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*","versionEndExcluding":"4.4.16","versionStartIncluding":"4.4.0","vulnerable":true},{"criteria":"cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*","versionEndExcluding":"4.5.9","versionStartIncluding":"4.5.0","vulnerable":true}],"negate":false,"operator":"OR"}],"operator":"OR"}],"cveId":"CVE-2026-41259","cwes":["CWE-841"],"description":"Mastodon is a free, open-source social network server based on ActivityPub. Prior to v4.5.9, v4.4.16, and v4.3.22, Mastodon allows restricting new user sign-up based on e-mail domain names, and performs basic validation on e-mail addresses, but fails to restrict characters that are interpreted differently by some mailing servers. This vulnerability is fixed in v4.5.9, v4.4.16, and v4.3.22.","epss":null,"exploits":[],"kev":null,"metrics":[{"score":8.2,"severity":"high","source":"NVD: security-advisories@github.com","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","version":"4.0"},{"score":7.5,"severity":"high","source":"NVD: nvd@nist.gov","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N","version":"3.1"}],"modifiedAt":1794438600263,"publishedAt":1776971850027,"references":[{"source":"security-advisories@github.com","tags":["Vendor Advisory"],"url":"https://github.com/mastodon/mastodon/security/advisories/GHSA-5r37-qpwq-2jhh"}],"remediation":[],"revision":"2a89f18d049eb7158dc5e17a73ef558211aead54aa498135eebbf6a21d2f957e","sources":[{"modifiedAt":1794438600263,"name":"NVD","retrievedAt":1794442757732,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-41259"}],"ssvc":{"assessedAt":1776972236034,"automatable":"yes","exploitation":"none","source":"NVD SSVC: 134c704f-9b21-4f2e-91b3-4a467353bcc0","technicalImpact":"partial"},"status":"published","title":"CVE-2026-41259","updatedAt":1794442757732}