CVE-2019-9815: mozilla firefox Observable Discrepancy
Vulnerability summary
CVE-2019-9815 is a high (CVSS 8.1) Observable Discrepancy vulnerability in mozilla firefox. EPSS estimates a 1.83% chance of exploitation in the next 30 days, higher than 78.6% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 8 · Related 8Timeline
- 23-07-2019PublishedVulnerability first disclosed.
- 04-08-2024Last modifiedVulnerability information updated.
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 metrics
3 scores · 2 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated8.1HighCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS trend
Probability
1.83%
Chance of exploitation in the next 30 days
Percentile
79%
Versus all other CVEs
30-day change
+0.26 pp
From 1.57% on 21-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Mozilla3 products
- firefox≥ unspecified, < 67 | < 67.0
- firefox_esr≥ unspecified, < 60.7 | < 60.7
- thunderbird≥ unspecified, < 60.7 | < 60.7
Ubuntu2 products
- mozjs38All versions (No fix recorded)
- mozjs52All versions (No fix recorded)
2 vendors · 5 products
References
9 links- bugzilla.mozilla.org/show_bug.cgi?id=1546544X Refsource MISCPermissions RequiredThird Party Advisory