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CVE-2021-3711

79
FAUCET Score

CVE-2021-3711 is a critical buffer overflow vulnerability in OpenSSL versions 1.1.1 through 1.1.1k, affecting products from vendors like Debian, NetApp, Oracle, and Tenable. This flaw occurs during SM2 decryption when the initial buffer size calculation is incorrect, leading to a potential overflow of up to 62 bytes. With a CVSS score of 9.8, it presents a high-impact risk (confidentiality, integrity, availability) via a low-complexity network attack, allowing an attacker to alter application behavior or cause crashes. While there is no known active exploitation or public exploit code (Metasploit, Nuclei, ExploitDB), the vulnerability has garnered significant community discussion and media coverage, indicating high awareness.

Impacted Technologies

VendorProductVersion(s)CPE
>= 1.1.1, < 1.1.1lCPE matchmatch criteria
cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*
10.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
11.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:vmware_vsphere:*:*
Range not provided by sourceCPE matchmatch criteria
cpe:2.3:a:netapp:active_iq_unified_manager:-:*:*:*:*:windows:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
87.82%
Probability of exploitation in next 30 days
EPSS Percentile
99.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.8782 is in the 99th percentile among its peer group of 36,862 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (9)

microsoftpatch availablevia msrc
Product: Microsoft Visual Studio 2022 version 17.0Fixed in: 17.0.7
View patch
microsoftpatch availablevia msrc
Product: Microsoft Visual Studio 2019 version 16.9 (includes 16.0 - 16.8)Fixed in: 16.9.13
View patch
microsoftpatch availablevia msrc
Product: Microsoft Visual Studio 2019 version 16.11 (includes 16.0 - 16.10)Fixed in: 16.11.6
View patch
microsoftpatch availablevia msrc
Product: Microsoft Visual Studio 2022 version 17.1Fixed in: 17.1.1
View patch
microsoftpatch availablevia msrc
Product: Microsoft Visual Studio 2017 version 15.9 (includes 15.0 - 15.8)Fixed in: 15.9.41
View patch
microsoftpatch availablevia msrc
Product: Microsoft Visual Studio 2019 version 16.7 (includes 16.0 – 16.6)Fixed in: 16.7.21
View patch
oraclepatch availablevia nvd_reference
View patch
rustpatch availablevia ghsa
Product: openssl-srcFixed in: 111.16.0
redhatno patchvia redhat_api
Product: Red Hat Advanced Cluster Management for Kubernetes 2Fixed in: rhacm2/management-ingress-rhel8

Vendor Advisories (3)

rustGHSA-5ww6-px42-wc85critical

SM2 Decryption Buffer Overflow

May 24, 2022
microsoft2021-Nov/CVE-2021-3711Critical

OpenSSL: CVE-2021-3711 SM2 Decryption Buffer Overflow

Nov 9, 2021
redhatCVE-2021-3711Important

openssl: SM2 Decryption Buffer Overflow

Aug 24, 2021

References

cert-portal.siemens.com / productcert/pdf/ssa-389290.pdf
Third Party Advisory
git.openssl.org / gitweb
lists.apache.org / thread.html/r18995de860f0e63635f3008fd2a6aca82394249476d21691e7c59c9e%40%3Cdev.tomcat.apache.org%3E
lists.apache.org / thread.html/rad5d9f83f0d11fb3f8bb148d179b8a9ad7c6a17f18d70e5805a713d1%40%3Cdev.tomcat.apache.org%3E
security.gentoo.org / glsa/202209-02
Third Party Advisory
security.gentoo.org / glsa/202210-02
Third Party Advisory
security.netapp.com / advisory/ntap-20210827-0010
Third Party Advisory
security.netapp.com / advisory/ntap-20211022-0003
Third Party Advisory
security.netapp.com / advisory/ntap-20240621-0006
debian.org / security/2021/dsa-4963
Third Party Advisory
openssl.org / news/secadv/20210824.txt
Vendor Advisory
oracle.com / security-alerts/cpuapr2022.html
PatchThird Party Advisory
oracle.com / security-alerts/cpujan2022.html
PatchThird Party Advisory
oracle.com / security-alerts/cpuoct2021.html
PatchThird Party Advisory
tenable.com / security/tns-2021-16
Third Party Advisory
tenable.com / security/tns-2022-02
Third Party Advisory
openwall.com / lists/oss-security/2021/08/26/2
Mailing ListThird Party Advisory