What’s Vulnerable › Vulnerabilities

CVE-2020-12402

• Severity: medium (CVSS 4.4 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-07-09 · updated 2026-06-17
• Weakness: CWE-203

Description

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.

Affected products

• Debian Linux: 9.0
• Fedoraproject Fedora: 32
• Mozilla Firefox: before 78.0 — fixed in 78.0
• openSUSE Leap: 15.1, 15.2

How to fix

Upgrade to a fixed version: Mozilla Firefox 78.0. Check the vendor advisory for mitigations.

References

• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00016.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00018.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.html
• https://bugzilla.mozilla.org/show_bug.cgi?id=1631597
• https://lists.debian.org/debian-lts-announce/2020/09/msg00029.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/RFL6UNFK4MG2WDXLMLFAEIUSM5EUK7CG/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/UWVDJRARXNWWWTCGMM63EXLQHH2LNOXO/
• https://security.gentoo.org/glsa/202007-10
• https://usn.ubuntu.com/4417-1/
• https://usn.ubuntu.com/4417-2/
• https://www.debian.org/security/2020/dsa-4726

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