medium 4.4

CVE-2020-12402 json

During RSA key generation, bignum implementations used a variation of the Binary Extended Euclidean Algorithm which entailed significantly…

published 2020-07-09 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-4714

cvss: 4.4; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 27%
public exploits: 0; none known

During RSA key generation, bignum implementations used a variation of the Binary Extended Euclidean Algorithm which entailed significantly input-dependent flow. This allowed an attacker able to perform electromagnetic-based side channel attacks to record traces leading to the recovery of the secret primes. *Note:* An unmodified Firefox browser does not generate RSA keys in normal operation and is not affected, but products built on top of it might. This vulnerability affects Firefox < 78.

Patch / fix

fixed in 1 distros 7

Mozilla Firefox 78

debian ubuntu red hat suse opensuse rocky linux alpine

nss Debian 14, Debian 13, Debian 12 2:3.53.1-1

debian advisories DEBIAN-CVE-2020-12402

nss Ubuntu 16.04 LTS 2:3.28.4-0ubuntu0.16.04.12
nss Ubuntu 18.04 LTS 2:3.35-2ubuntu2.9
nss Ubuntu 20.04 LTS 2:3.49.1-1ubuntu1.2
nss Ubuntu Pro 14.04 LTS 2:3.28.4-0ubuntu0.14.04.5+esm6

ubuntu advisories UBUNTU-CVE-2020-12402

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

nss RHEL 7 3.53.1-3.el7_9
nspr RHEL 7 4.25.0-2.el7_9
nss-util RHEL 7 3.53.1-1.el7_9
nss-tools RHEL 7 3.53.1-3.el7_9
nss-softokn RHEL 7 3.53.1-6.el7_9
nss-sysinit RHEL 7 3.53.1-3.el7_9
nss-softokn-freebl RHEL 7 3.53.1-6.el7_9
nss RHEL 8 3.53.1-11.el8_2

red hat advisories RHSA-2020:4076 RHSA-2020:3280

MozillaFirefox SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +15 more 78.0.1-112.3.1
MozillaFirefox-branding-SLE SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +14 more 78-35.3.1
MozillaFirefox SLE Module for Desktop Applications 15 SP2, SLE Module for Desktop Applications 15 SP1 78.0.1-3.94.2
MozillaFirefox-branding-SLE SLE Module for Desktop Applications 15 SP2, SLE Module for Desktop Applications 15 SP1 78-4.14.1
mozilla-nss SLES for SAP 15, SLES 15-LTSS, SLE Module for Server Applications 15 SP2 +5 more 3.53.1-3.45.1
mozilla-nss SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +15 more 3.53.1-58.48.1
mozilla-nspr SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +15 more 4.25-19.15.1
MozillaFirefox SLES 11 SP4-LTSS 78.0.1-78.80.2

suse advisories SUSE-SU-2020:1899-1 SUSE-SU-2020:1898-1 SUSE-SU-2020:14421-1 SUSE-SU-2020:14418-1 SUSE-SU-2020:1850-1 SUSE-SU-2020:1839-1

firefox-esr openSUSE Tumbleweed 128.5.1-1.1
MozillaFirefox openSUSE Tumbleweed 92.0-1.2
mozilla-nss openSUSE Tumbleweed 3.69.1-1.2
MozillaFirefox openSUSE Leap 15.1 78.0.1-lp151.2.53.1
MozillaFirefox openSUSE Leap 15.2 78.0.1-lp152.2.5.1
mozilla-nss openSUSE Leap 15.2 3.53.1-lp152.2.4.1
mozilla-nss openSUSE Leap 15.1 3.53.1-lp151.2.26.1

opensuse advisories openSUSE-SU-2024:14572-1 openSUSE-SU-2024:10600-1 openSUSE-SU-2024:11058-1 openSUSE-SU-2020:1017-1 openSUSE-SU-2020:0983-1 openSUSE-SU-2020:0955-1

nspr Rocky Linux 8 4.25.0-2.el8_2

rocky linux advisories RLSA-2020:3280

nss Alpine 3.24, Alpine 3.23, Alpine 3.22 +10 more 3.53.1-r0
firefox Alpine 3.23, Alpine 3.22, Alpine 3.21 +9 more 78.0-r0
librewolf Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 78.0-r0

alpine advisories ALPINE-CVE-2020-12402

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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-2020-12402 updated 2026-11-05 cvss 4.4

nss: Side channel vulnerabilities during RSA key generation

Red Hat Enterprise Linux 5 nss Red Hat Enterprise Linux 6 nss, nss-tools, nss-sysinit
affected: workaround, no fix planned “Out of support scope”
Red Hat OpenShift Do 1 openshiftdo/odo-init-image-rhel7 1.1.3-2
fixed: vendor fix RHSA-2021:0949
Red Hat Enterprise Linux AppStream (v. 8) nspr 4.25.0-2.el8_2, nss 3.53.1-11.el8_2, nss-util 3.53.1-11.el8_2, nss-tools 3.53.1-11.el8_2, nss-softokn 3.53.1-11.el8_2, nss-sysinit 3.53.1-11.el8_2, +1 more
fixed: vendor fix RHSA-2020:3280
Red Hat Enterprise Linux Client (v. 7) nss 3.53.1-3.el7_9, nspr 4.25.0-2.el7_9, nss-util 3.53.1-1.el7_9, nss-tools 3.53.1-3.el7_9, nss-softokn 3.53.1-6.el7_9, nss-sysinit 3.53.1-3.el7_9, +1 more Red Hat Enterprise Linux Client Optional (v. 7) nss-devel 3.53.1-3.el7_9, nspr-devel 4.25.0-2.el7_9, nss-debuginfo 3.53.1-3.el7_9, nspr-debuginfo 4.25.0-2.el7_9, nss-util-devel 3.53.1-1.el7_9, nss-pkcs11-devel 3.53.1-3.el7_9, +4 more Red Hat Enterprise Linux ComputeNode Optional (v. 7) nss-devel 3.53.1-3.el7_9, nspr-devel 4.25.0-2.el7_9, nss-debuginfo 3.53.1-3.el7_9, nspr-debuginfo 4.25.0-2.el7_9, nss-util-devel 3.53.1-1.el7_9, nss-pkcs11-devel 3.53.1-3.el7_9, +4 more Red Hat Enterprise Linux Server (v. 7) nss 3.53.1-3.el7_9, nspr 4.25.0-2.el7_9, nss-util 3.53.1-1.el7_9, nss-tools 3.53.1-3.el7_9, nss-softokn 3.53.1-6.el7_9, nss-sysinit 3.53.1-3.el7_9, +1 more Red Hat Enterprise Linux Server Optional (v. 7) nss-debuginfo 3.53.1-3.el7_9, nss-pkcs11-devel 3.53.1-3.el7_9 Red Hat Enterprise Linux Workstation (v. 7) nss 3.53.1-3.el7_9, nspr 4.25.0-2.el7_9, nss-util 3.53.1-1.el7_9, nss-tools 3.53.1-3.el7_9, nss-softokn 3.53.1-6.el7_9, nss-sysinit 3.53.1-3.el7_9, +1 more

+1 more productsfewer

Red Hat Enterprise Linux Workstation Optional (v. 7) nss-debuginfo 3.53.1-3.el7_9, nss-pkcs11-devel 3.53.1-3.el7_9

fixed: vendor fix RHSA-2020:4076
Red Hat OpenShift Container Platform 4 nss-altfiles
not affected: vulnerable code not present

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

0.34% chance of exploitation in the next 30 days, higher than 27% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.1	4.4	CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:N/A:N
NVD	2.0	1.2	AV:L/AC:H/Au:N/C:P/I:N/A:N

Affected products

Mozilla Firefox

Classification

Weakness

CWE-203 Observable Discrepancy

References

lists.opensuse.org /opensuse-security-announce/2020-07/msg00016.html
vendor-advisory, third-party-advisory
lists.opensuse.org /opensuse-security-announce/2020-07/msg00018.html
vendor-advisory, third-party-advisory
usn.ubuntu.com /4417-1/
vendor-advisory, third-party-advisory
lists.opensuse.org /opensuse-security-announce/2020-07/msg00027.html
vendor-advisory, third-party-advisory
debian.org /security/2020/dsa-4726
vendor-advisory, third-party-advisory
lists.fedoraproject.org /archives/list/package-announce%40lists.fedoraproject.org/message/UWVDJRARXNWWWTCGMM63EXLQHH2LNOXO/
vendor-advisory
lists.opensuse.org /opensuse-security-announce/2020-07/msg00049.html
vendor-advisory, third-party-advisory
security.gentoo.org /glsa/202007-10
vendor-advisory, third-party-advisory
usn.ubuntu.com /4417-2/
vendor-advisory, third-party-advisory
lists.fedoraproject.org /archives/list/package-announce%40lists.fedoraproject.org/message/RFL6UNFK4MG2WDXLMLFAEIUSM5EUK7CG/
vendor-advisory
mozilla.org /security/advisories/mfsa2020-24/
vendor-advisory
bugzilla.mozilla.org /show_bug.cgi?id=1631597
issue-tracking, permissions-required, vendor-advisory
lists.debian.org /debian-lts-announce/2020/09/msg00029.html
mailing-list, third-party-advisory

Sources

CVE List CVE-2020-12402
NVD CVE-2020-12402

Fencer Vulns 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.

Summary