Vulnerability in Mozilla Firefox

CVE-2019-11727

A vulnerability exists where it possible to force Network Security Services (NSS) to sign CertificateVerify with PKCS#1 v1.5 signatures when those are the only ones advertised by server in CertificateRequest in TLS 1.3. PKCS#1 v1.5 signatures should not be used for TLS 1.3 messages. This vulnerability affects Firefox < 68.

Vulnerability class: Improper Certificate Validation

EPSS: 0.017 (75.4th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2019-11727?
CVE-2019-11727 is a medium-severity vulnerability in Mozilla Firefox, classified under Improper Certificate Validation. CVSS score: 5.3/10. Published 2019-07-23.
How severe is CVE-2019-11727?
Medium severity. CVSS v3 base score is 5.3 out of 10.
Is CVE-2019-11727 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.