CVE-2019-9791

critical
Published — · Modified —
CVSS v3
CVSS v2
VIR risk
9.5

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.

Predictions

Exploit likelihood
20%
Patch ETA

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

vendor Authored 2026-05-27

Vendor advisory: debian — https://security-tracker.debian.org/tracker/CVE-2019-9791

vendor Authored 2026-05-27

Vendor advisory: suse — https://www.suse.com/security/cve/CVE-2019-9791.html

vendor Authored 2026-05-27

Vendor advisory: arch — https://security.archlinux.org/ASA-201903-11

OS impact

OSVersionStatusFixed in
arch archfixed66.0-1
suse slesaffected
debian debiansidfixed66.0-1
debian debianbookwormfixed60.6.0esr-1
debian debianbullseyefixed60.6.0esr-1
debian debianforkyfixed60.6.0esr-1
debian debiantrixiefixed60.6.0esr-1

References

Verify integrity in audit chain (admin only). AS-IS.