CVE-2019-9791
The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack…
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 19.9%, higher than 97% of all known CVEs. Patch or mitigate before the next change window.
Description
The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). This allows for possible arbitrary reading and writing of objects during an exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 19.91% probability · 97th percentile
- Public exploits
- 1 in Exploit-DB · verified · first 26 March 2019
- CISA KEV
- Not listed
- Weakness
- CWE-843
- Affected
- mozilla/firefox · mozilla/thunderbird · redhat/enterprise linux · redhat/enterprise linux eus · redhat/enterprise linux server aus · redhat/enterprise linux server tus
- Source
- security@mozilla.org
EPSS 19.9% since 26 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
Public exploits (1)
Entries in Exploit-DB that cite this CVE. Links go to the Exploit-DB page and to the file in the public repository; nothing is hosted here. A verified tick means the Exploit-DB team confirmed the exploit works against the stated version.
References
- https://access.redhat.com/errata/RHSA-2019:0966Third Party Advisory
- https://access.redhat.com/errata/RHSA-2019:1144Third Party Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1530958Exploit, Issue Tracking, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-07/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-08/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-11/Vendor Advisory
- https://access.redhat.com/errata/RHSA-2019:0966Third Party Advisory
- https://access.redhat.com/errata/RHSA-2019:1144Third Party Advisory
- https://bugzilla.mozilla.org/show_bug.cgi?id=1530958Exploit, Issue Tracking, Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-07/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-08/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2019-11/Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.