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 6y ago modified 2026-06-17 4mo 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

Is CVE-2020-12402 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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, 2026-11-09).

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 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.

json all entries feed