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CVE-2021-4160

25
FAUCET Score

CVE-2021-4160 is a medium-severity carry propagation bug in the MIPS32 and MIPS64 squaring procedure within OpenSSL versions 1.0.2, 1.1.1, and 3.0.0, primarily affecting MIPS platforms. This vulnerability could potentially impact various Elliptic Curve (EC) algorithms, including those used in TLS 1.3, and could theoretically allow for difficult attacks against Diffie-Hellman (DH) to deduce private key information. The CVSS score is 5.9 (MEDIUM) due to high confidentiality impact but high attack complexity and no user interaction required. While attacks against RSA and DSA are considered highly improbable, and meaningful TLS attacks are mitigated by prior CVEs, the vulnerability has been patched in OpenSSL versions 1.1.1m, 3.0.1, and 1.0.2zc-dev. There is currently no evidence of active exploitation, publicly available exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
>= 1.0.2, <= 1.0.2zbCPE matchmatch criteria
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
>= 1.1.1, < 1.1.1mCPE matchmatch criteria
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
3.0.0CPE matchmatch criteria
cpe:2.3:a:openssl:openssl:3.0.0:-:*:*:*:*:*:*
3.0.0CPE matchmatch criteria
cpe:2.3:a:openssl:openssl:3.0.0:alpha1:*:*:*:*:*:*
3.0.0CPE matchmatch criteria
cpe:2.3:a:openssl:openssl:3.0.0:alpha10:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.9MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
3.80%
Probability of exploitation in next 30 days
EPSS Percentile
88.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0380 is in the 85th percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (15)

microsoftpatch availablevia msrc
Product: azl3 edk2 20230301gitf80f052277c8-37 on Azure Linux 3.0Fixed in: 20240223gitedc6681206c1-2
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 1.1.1k-8
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 1.1.1k-8
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 x64Fixed in: 1.1.1k-13
microsoftpatch availablevia msrc
Product: CBL Mariner 2.0 ARMFixed in: 1.1.1k-13
microsoftpatch availablevia msrc
Product: Azure Linux 3.0 x64Fixed in: 20240223gitedc6681206c1-2
microsoftpatch availablevia msrc
Product: Azure Linux 3.0 ARMFixed in: 20240223gitedc6681206c1-2
microsoftpatch availablevia msrc
Product: 18903-16820Fixed in: -
microsoftpatch availablevia msrc
Product: 18904-16823Fixed in: -
microsoftpatch availablevia msrc
Product: 18830-17084Fixed in: 20240223gitedc6681206c1-2
microsoftpatch availablevia msrc
Product: 17859-17084Fixed in: 20240223gitedc6681206c1-2
microsoftpatch availablevia msrc
Product: cm1 openssl 1.1.1k-8 on CBL Mariner 1.0Fixed in: -
microsoftpatch availablevia msrc
Product: cbl2 openssl 1.1.1k-13 on CBL Mariner 2.0Fixed in: -
microsoftpatch availablevia msrc
Product: azl3 edk2 20240223gitedc6681206c1-2 on Azure Linux 3.0Fixed in: 20240223gitedc6681206c1-2
oraclepatch availablevia nvd_reference
View patch

Vendor Advisories (3)

microsoft2024-Sep/CVE-2021-4160

CVE-2021-4160

Sep 10, 2024
redhatCVE-2021-4160Low

openssl: Carry propagation bug in the MIPS32 and MIPS64 squaring procedure

Jan 28, 2022
microsoft2022-Jan/CVE-2021-4160Moderate

BN_mod_exp may produce incorrect results on MIPS

Jan 11, 2022

References

cert-portal.siemens.com / productcert/pdf/ssa-637483.pdf
Third Party Advisory
git.openssl.org / gitweb
git.openssl.org / gitweb
git.openssl.org / gitweb
security.gentoo.org / glsa/202210-02
Third Party Advisory
security.netapp.com / advisory/ntap-20240621-0006
debian.org / security/2022/dsa-5103
Third Party Advisory
openssl.org / news/secadv/20220128.txt
Vendor Advisory
oracle.com / security-alerts/cpuapr2022.html
PatchThird Party Advisory
oracle.com / security-alerts/cpujul2022.html
Third Party Advisory