CVE-2019-9815
If hyperthreading is not disabled, a timing attack vulnerability exists, similar to previous Spectre attacks.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.83%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
If hyperthreading is not disabled, a timing attack vulnerability exists, similar to previous Spectre attacks. Apple has shipped macOS 10.14.5 with an option to disable hyperthreading in applications running untrusted code in a thread through a new sysctl. Firefox now makes use of it on the main thread and any worker threads. *Note: users need to update to macOS 10.14.5 in order to take advantage of this change.*. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.
- CVSS 3.0
- 8.1 HIGHCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 1.83% probability · 79th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-203
- Affected
- mozilla/firefox · mozilla/firefox esr · mozilla/thunderbird
- Source
- security@mozilla.org
EPSS 1.8% since 26 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
- https://bugzilla.mozilla.org/show_bug.cgi?id=1546544Permissions Required, Third Party Advisory
- https://mdsattacks.com/Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-13/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-14/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-15/Vendor Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1546544Permissions Required, Third Party Advisory
- https://mdsattacks.com/Third Party Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-13/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-14/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-15/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.