PatchTheCEVCVE-2025-6430: When a file download is specified via the `Content-Disposition` header, that directive would be ignored if the
26
Routine
MEDIUM 6.1UPGRADE
CVE-2025-6430 is a medium-severity flaw (CVSS 6.1) affecting firefox. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- No elevated risk signals yet
A fixed release or distro patch exists.
Risk facts
| CVSS score | 6.1 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | Required |
| EPSS exploit chance | 0.3% (top 82%) |
| CISA exploited list | No |
| Weakness | CWE-79 |
| Published | 2025-06-24 |
| Last modified | 2026-10-23 |
Publisher (CNA): Mozilla Corporation · Vendor: mozilla
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
mozilla firefox UPGRADE
Affected: < 128.12.0 · < 140.0
Fixed in: 128.12.0, 140.0
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy firefox || rpm -q firefox || firefox --version
2. UPGRADE to 128.12.0 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade firefox
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade firefox
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Related CVEs
- CVE-2023-4050 HIGH 7.5 UPGRADE MITIGATE In some cases, an untrusted input stream was copied to a stack buffer without checking its size
- CVE-2023-29542 CRITICAL 9.8 UPGRADE UPGRADE A newline in a filename could have been used to bypass the file extension security mechanisms that replace mal
- CVE-2025-11708 CRITICAL 9.8 UPGRADE UPGRADE Use-after-free in MediaTrackGraphImpl::GetInstance()
- CVE-2026-5734 CRITICAL 9.8 UPGRADE UPGRADE Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 14
- CVE-2026-5735 CRITICAL 9.8 UPGRADE UPGRADE Memory safety bugs present in Firefox 149.0.1 and Thunderbird 149.0.1