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CVE-2019-9821A use-after-free vulnerability can occur in AssertWorkerThread due to a race condition with shared workers. This results in a potentially…
- 8.1HighCVSS base score
- 0.85%Exploitation in 30 daysEPSS · top 41% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
A use-after-free vulnerability can occur in AssertWorkerThread due to a race condition with shared workers. This results in a potentially exploitable crash. This vulnerability affects Firefox < 67.
Timeline
ID reserved
By mozilla
- 4 months later
· 4 months later
Published
- 5 years later
· 5 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.0 | High8.1 | CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.85% · top 41% of all CVEs (14 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.1.
Affected products
References
References2
- https://www.mozilla.org/security/advisories/mfsa2019-13/ (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.mozilla.org/show_bug.cgi?id=1539125 (opens in a new tab)x_refsource_MISCx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2019-19183 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2019-9821)Record last updated .