CVE-2019-9792
The IonMonkey just-in-time (JIT) compiler can leak an internal JS_OPTIMIZED_OUT magic value to the running script during a bailout.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 13.2%, higher than 96% of all known CVEs. Patch or mitigate before the next change window.
Description
The IonMonkey just-in-time (JIT) compiler can leak an internal JS_OPTIMIZED_OUT magic value to the running script during a bailout. This magic value can then be used by JavaScript to achieve memory corruption, which results in a potentially 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
- 13.20% probability · 96th percentile
- Public exploits
- 1 in Exploit-DB · verified · first 29 May 2019
- CISA KEV
- Not listed
- Weakness
- CWE-787
- 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 13.2% 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
- http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.htmlExploit, Third Party Advisory, VDB Entry
- 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=1532599Exploit, 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
- http://packetstormsecurity.com/files/153106/Spidermonkey-IonMonkey-JS_OPTIMIZED_OUT-Value-Leak.htmlExploit, Third Party Advisory, VDB Entry
- 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=1532599Exploit, 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.