CVE-2024-3863: Mozilla Firefox · Unrestricted File Upload
Affects Mozilla FirefoxSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical.
Data as of 4 Nov 2026, 00:28 UTC
Thin evidence
One scorer or none| CISA-ADP | CVSS 3.1 | 9.8 |
|---|
- EPSS
- 0.8% chance of exploitation in 30 days – higher than 57% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2025-08-22.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 16 Apr 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 3 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| MozillaFirefox | Affected
| Fixed in– |
| MozillaFirefox ESR | Affected
| Fixed in– |
| MozillaThunderbird | Affected
| Fixed in– |
AI-suggested
This vulnerability has been fixed in Firefox 125, Firefox ESR 115.10, and Thunderbird 115.10. Users and administrators should update affected Mozilla products to these versions or later to mitigate the risk. No additional mitigation steps are required beyond applying the official patches.
Description
The executable file warning was not presented when downloading .xrm-ms files. *Note: This issue only affected Windows operating systems. Other operating systems are unaffected.* This vulnerability affects Firefox < 125, Firefox ESR < 115.10, and Thunderbird < 115.10.