CVE-2017-7821
A vulnerability where WebExtensions can download and attempt to open a file of some non-executable file types.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.91%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
A vulnerability where WebExtensions can download and attempt to open a file of some non-executable file types. This can be triggered without specific user interaction for the file download and open actions. This could be used to trigger known vulnerabilities in the programs that handle those document types. This vulnerability affects Firefox < 56.
- CVSS 3.0
- 9.8 CRITICALCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 1.91% probability · 80th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-732
- Affected
- mozilla/firefox
- Source
- security@mozilla.org
EPSS 1.9% since 27 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://www.securityfocus.com/bid/101057Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1039465Third Party Advisory, VDB Entry
- https://bugzilla.mozilla.org/show_bug.cgi?id=1346515Exploit, Issue Tracking
- https://www.mozilla.org/security/advisories/mfsa2017-21/Vendor Advisory
- http://www.securityfocus.com/bid/101057Third Party Advisory, VDB Entry
- http://www.securitytracker.com/id/1039465Third Party Advisory, VDB Entry
- https://bugzilla.mozilla.org/show_bug.cgi?id=1346515Exploit, Issue Tracking
- https://www.mozilla.org/security/advisories/mfsa2017-21/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.