Firefox Developer Edition (en-US) 140.0
Firefox Developer Edition (en-US) 140.0, released June 13, 2025, fixes 12 CVEs in Firefox Developer Edition (en-US). None of them is reported as exploited. Patch Radar priority: Urgent. The latest Firefox Developer Edition (en-US) is 156.0, which also fixes every one of these CVEs.
Superseded. The latest Firefox Developer Edition (en-US) is 156.0, which also fixes every CVE on this page. Install that instead.
Priority of the 12 CVEs
Applies to
| Product | Version |
|---|---|
| Firefox Developer Edition (en-US) | 140.0 |
CVEs this fix closes
| Priority | CVE | Title | CVSS | EPSS | Exploitation |
|---|---|---|---|---|---|
| Urgent | CVE-2025-49710 | Integer overflow in OrderedHashTable | 9.8 | 0.0075 | None reported |
| Urgent | CVE-2025-49709 | Memory corruption in canvas surfaces | 9.8 | 0.0067 | None reported |
| High | CVE-2025-6424 | Use-after-free in FontFaceSet | 9.8 | 0.0796 | None reported |
| High | CVE-2025-6436 | Memory safety bugs fixed in Firefox 140 and Thunderbird 140 | 8.1 | 0.0426 | None reported |
| High | CVE-2025-6435 | Save as in Devtools could download files without sanitizing the extension | 8.1 | 0.0046 | None reported |
| High | CVE-2025-6427 | connect-src Content Security Policy restriction could be bypassed | 9.1 | 0.0037 | None reported |
| High | CVE-2025-6429 | Incorrect parsing of URLs could have allowed embedding of youtube.com | 7.5 | 0.0036 | None reported |
| High | CVE-2025-6432 | DNS Requests leaked outside of a configured SOCKS proxy | 8.6 | 0.0035 | None reported |
| High | CVE-2025-6425 | The WebCompat WebExtension shipped with Firefox exposed a persistent UUID | 7.5 | 0.0031 | None reported |
| High | CVE-2025-6433 | WebAuthn would allow a user to sign a challenge on a webpage with an invalid TLS certificate | 9.8 | 0.0030 | None reported |
| High | CVE-2025-6430 | Content-Disposition header ignored when a file is included in an embed or object tag | 7.5 | 0.0027 | None reported |
| Routine | CVE-2025-6434 | HTTPS-Only exception screen lacked anti-clickjacking delay | 4.3 | 0.0028 | None reported |
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