Buffer overflow in Mozilla Firefox

CVE-2019-11759

An attacker could have caused 4 bytes of HMAC output to be written past the end of a buffer stored on the stack. This could be used by an attacker to execute arbitrary code or more likely lead to a crash. This vulnerability affects Firefox < 70, Thunderbird < 68.2, and Firefox ESR < 68.2.

Vulnerability class: Buffer Overflow

EPSS: 0.018 (76.2th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2019-11759?
CVE-2019-11759 is a high-severity vulnerability in Mozilla Firefox, classified under Buffer Copy without Checking Size of Input (Classic Buffer Overflow). CVSS score: 8.8/10. Published 2020-01-08.
How severe is CVE-2019-11759?
High severity. CVSS v3 base score is 8.8 out of 10.
Is CVE-2019-11759 known to be exploited?
3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.