CVE-2021-4160 BN_mod_exp may produce incorrect results on MIPS

What is CVE-2021-4160?

CVE-2021-4160 is a medium-severity vulnerability in Debian Debian Linux, published on 28 Jan 2022. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

There is a carry propagation bug in the MIPS32 and MIPS64 squaring procedure. Many EC algorithms are affected, including some of the TLS 1.3 default curves. Impact was not analyzed in detail, because the pre-requisites for attack are considered unlikely and include reusing private keys. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH are considered just feasible (although very difficult) because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be significant. However, for an attack on TLS to be meaningful, the server would have to share the DH private key among multiple clients, which is no longer an option since CVE-2016-0701. This issue affects OpenSSL versions 1.0.2, 1.1.1 and 3.0.0. It was addressed in the releases of 1.1.1m and 3.0.1 on the 15th of December 2021. For the 1.0.2 release it is addressed in git commit 6fc1aaaf3 that is available to premium support customers only. It will be made available in 1.0.2zc when it is released. The issue only affects OpenSSL on MIPS platforms. Fixed in OpenSSL 3.0.1 (Affected 3.0.0). Fixed in OpenSSL 1.1.1m (Affected 1.1.1-1.1.1l). Fixed in OpenSSL 1.0.2zc-dev (Affected 1.0.2-1.0.2zb).

Which versions are affected by CVE-2021-4160?

It affects 8 products.

Products include Debian Debian Linux, Openssl Openssl, Oracle Enterprise Manager Ops Center, Oracle Health Sciences Inform Publisher, Oracle Jd Edwards Enterpriseone Tools, Oracle Jd Edwards World Security and 2 more.

How do I fix CVE-2021-4160?

Upgrade to a fixed version.

Is CVE-2021-4160 being exploited?

There is no known exploitation of CVE-2021-4160 in the wild and no public exploit code.

Other vulnerabilities in Debian Debian Linux

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• CVE-2025-49113 RoundCube Webmail Deserialization of Untrusted Data Exploited Critical 9.9
• CVE-2026-24061 GNU InetUtils Argument Injection Exploited Critical 9.8
• CVE-2025-39682 Linux Kernel Improper Check for Unusual or Exceptional Conditions Exploited Critical 9.8
• CVE-2024-9680 Mozilla Firefox Use-After-Free Exploited Critical 9.8

All Debian Debian Linux vulnerabilities

Sources

• CVE record
• NVD
• OSV
• GitHub advisory
• How this page is made

Also known as AZL-8472, DEBIAN-CVE-2021-4160, GHSA-ph2x-8239-7xc7, JLSEC-2026-226, UBUNTU-CVE-2021-4160.