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No exploitation reportedFix available

CVE-2019-9815

No exploitation reported by the sources we read.

  • Published2019-07-23
  • Fixed in67.0
  • WeaknessCWE-203

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2019-07-2314:15CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2019-9815?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2019-9815?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Mozilla firefoxversion to verify
BranchAffectedFixed in
67.0< 67.067.0
Mozilla firefox esrversion to verify
BranchAffectedFixed in
60.7< 60.760.7
Mozilla thunderbirdversion to verify
BranchAffectedFixed in
60.7< 60.760.7

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Fix

  1. Update Mozilla firefox to 67.0

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
none listed
PoC-in-GitHub

Sources

  • NVDCVSS 3.08.1read 2026-10-23
  • NVDCVSS 2.06.8read 2026-10-23
  • NVDweakness (CWE)CWE-203read 2026-10-23
  • FIRST EPSSEPSS score1.8 %2026-10-23

Technical details

CVSS v3 Vector
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2019-07-23
Last Modified
2026-06-17
NVD status
Modified

Frequently asked questions

What is CVE-2019-9815?

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.

Is CVE-2019-9815 actively exploited?

Active exploitation of CVE-2019-9815 has not been confirmed. Its EPSS score was 1.8% on 2026-10-23, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2019-9815?

CVE-2019-9815 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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