CVE-2019-11727 — A vulnerability exists where it possible to force Network Security Services (NSS

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 messag

01What is this vulnerability?

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.

02Affected products

Vendor	Product	Versions
Mozilla	Firefox	unspecified

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2019-07-23T13:16:44.000Z
• Last modified: 2024-08-04T23:03:32.496Z

09References

• www.mozilla.org — https://www.mozilla.org/security/advisories/mfsa2019-21/
• bugzilla.mozilla.org — https://bugzilla.mozilla.org/show_bug.cgi?id=1552208
• access.redhat.com — https://access.redhat.com/errata/RHSA-2019:1951
• security.gentoo.org — https://security.gentoo.org/glsa/201908-12
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00010.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00009.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00011.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00017.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-01/msg00006.html