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Fencer Intel
medium 6.5

CVE-2016-1938 json

The s_mp_div function in lib/freebl/mpi/mpi.c in Mozilla Network Security Services (NSS) before 3.21, as used in Mozilla Firefox before 44.…

published 2016-01-31 10 y ago modified 2026-06-17 4 mo ago also EUVD-2016-3027

cvss
6.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
3.2%
EPSS 3.2% chance of exploitation in 30 days, percentile 88%
public exploits
0
none known

Summary

The s_mp_div function in lib/freebl/mpi/mpi.c in Mozilla Network Security Services (NSS) before 3.21, as used in Mozilla Firefox before 44.0, improperly divides numbers, which might make it easier for remote attackers to defeat cryptographic protection mechanisms by leveraging use of the (1) mp_div or (2) mp_exptmod function.

Patch / fix

  • nss Debian 14, Debian 13, Debian 12 2:3.21-1

debian advisories DEBIAN-CVE-2016-1938

  • nss Ubuntu 14.04 LTS 2:3.21-0ubuntu0.14.04.1
  • firefox Ubuntu 14.04 LTS 44.0+build3-0ubuntu0.14.04.1
  • thunderbird Ubuntu 14.04 LTS 1:38.8.0+build1-0ubuntu0.14.04.1
  • thunderbird Ubuntu 16.04 LTS 1:38.8.0+build1-0ubuntu0.16.04.1

ubuntu advisories UBUNTU-CVE-2016-1938

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • mozilla-nss SLES for SAP 11 SP4, SLES for SAP 11 SP3, SLES 11 SP4 +6 more 3.20.2-25.2
  • MozillaFirefox SLES for SAP 11 SP4, SLES for SAP 11 SP3, SLES 11 SP4 +6 more 38.6.0esr-31.3
  • MozillaFirefox-branding-SLED SLES for SAP 11 SP4, SLES for SAP 11 SP3, SLES 11 SP4 +4 more 38-18.24
  • mozilla-nss SLES for SAP 12 SP1, SLES for SAP 12, SLES 12 SP1 +5 more 3.20.2-37.1
  • MozillaFirefox SLES for SAP 12 SP1, SLES for SAP 12, SLES 12 SP1 +5 more 38.6.0esr-57.3
  • MozillaFirefox-branding-SLE SLES for SAP 12 SP1, SLES for SAP 12, SLES 12 SP1 +3 more 31.0-20.1
  • mozilla-nss SLES 11 SP2-LTSS 3.20.2-17.5
  • MozillaFirefox SLES 11 SP2-LTSS 38.6.1esr-33.1

suse advisories SUSE-SU-2016:0584-1SUSE-SU-2016:0334-1SUSE-SU-2016:0338-1

  • firefox-esr openSUSE Tumbleweed 128.5.1-1.1
  • MozillaFirefox openSUSE Tumbleweed 50.1.0-1.1

opensuse advisories openSUSE-SU-2024:14572-1openSUSE-SU-2024:10071-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2016-1938 updated cvss 2.6

NSS: Errors in mp_div and mp_exptmod cryptographic functions

  • Red Hat Enterprise Linux 5 nss Red Hat Enterprise Linux 6 nss-softokn, nss-softokn-freebl Red Hat Enterprise Linux 7 nss-softokn, nss-softokn-freebl
    affected: no fix planned “Will not fix”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.16% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.0 6.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
NVD 2.0 6.4 AV:N/AC:L/Au:N/C:P/I:P/A:N

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.