--- id: CVE-2025-6430 title: >- When a file download is specified via the `Content-Disposition` header, that directive would be ignored if the file was included via a `<embed>` or `<object>` tag, potentially making a website vulnerable to a cross-site scrip… summary: >- When a file download is specified via the `Content-Disposition` header, that directive would be ignored if the file was included via a `<embed>` or `<object>` tag, potentially making a website vulnerable to a cross-site scrip… severity: medium cvss: 6.1 cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N' cwe: - CWE-79 vendor: mozilla product: firefox affected: - firefox < 128.12.0 - firefox < 140.0 patched: - firefox 140.0 published: '2025-06-24' updated: '2026-09-30' sourceUpdated: '2026-09-30T18:10:00.190' source: NVD sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-6430' references: - url: 'https://bugzilla.mozilla.org/show_bug.cgi?id=1971140' label: security@mozilla.org - url: 'https://www.mozilla.org/security/advisories/mfsa2025-51/' label: security@mozilla.org - url: 'https://www.mozilla.org/security/advisories/mfsa2025-53/' label: security@mozilla.org - url: 'https://www.mozilla.org/security/advisories/mfsa2025-54/' label: security@mozilla.org - url: 'https://www.mozilla.org/security/advisories/mfsa2025-55/' label: security@mozilla.org - url: 'https://lists.debian.org/debian-lts-announce/2025/06/msg00029.html' label: af854a3a-2127-422b-91ae-364da2661108 - url: 'https://lists.debian.org/debian-lts-announce/2025/07/msg00002.html' label: af854a3a-2127-422b-91ae-364da2661108 tags: - nvd epss: 0.00268 epssPercentile: 0.17077 ingestedAt: '2026-09-30T18:17:24.444Z' --- ## Overview When a file download is specified via the `Content-Disposition` header, that directive would be ignored if the file was included via a `<embed>` or `<object>` tag, potentially making a website vulnerable to a cross-site scripting attack. This vulnerability was fixed in Firefox 140, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12. ## Affected - `firefox < 128.12.0` - `firefox < 140.0` ## Remediation Upgrade past the affected range: - `firefox 140.0`