CVE-2021-3711: Openssl src SM2 Decryption Buffer Overflow Vulnerability

CRITICAL
Advisory Identifier: GHSA-5ww6-px42-wc85
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CVSS 9.8
CWE-120
Published
Advisory Summary

CVE-2021-3711 is a CRITICAL (CVSS 9.8) sm2 decryption buffer overflow vulnerability (CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')) affecting Openssl src libraries in the crates.io ecosystem. The issue involves sm2 decryption buffer overflow. Remediation is available by upgrading affected packages to version 111.16.0.

CVE-2021-3711 at a Glance

CVE Identifier CVE-2021-3711
GHSA Identifier GHSA-5ww6-px42-wc85
Severity CRITICAL
CVSS v3.1 Base Score 9.8
CWE Classification CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
Affected Product Openssl src
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 9.8

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality High (C:H)
Integrity High (I:H)
Availability High (A:H)

How to Fix CVE-2021-3711

To remediate this vulnerability, upgrade all affected Openssl src dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

openssl-src fixed: 111.16.0 
Upgrade openssl-src to 111.16.0
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for openssl-src

How to Check if You Are Affected

To determine whether your application is affected by CVE-2021-3711, inspect your project dependencies for Openssl src:

inspect dependencies for openssl-src

Analyze the terminal output to locate any version of Openssl src in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 111.16.0), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow'), where the product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer. In Openssl src, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

In order to decrypt SM2 encrypted data an application is expected to call the API function EVP_PKEY_decrypt(). Typically an application will call this function twice. The first time, on entry, the "out" parameter can be NULL and, on exit, the "outlen" parameter is populated with the buffer size required to hold the decrypted plaintext. The application can then allocate a sufficiently sized buffer and call EVP_PKEY_decrypt() again, but this time passing a non-NULL value for the "out" parameter. A bug in the implementation of the SM2 decryption code means that the calculation of the buffer size required to hold the plaintext returned by the first call to EVP_PKEY_decrypt() can be smaller than the actual size required by the second call. This can lead to a buffer overflow when EVP_PKEY_decrypt() is called by the application a second time with a buffer that is too small. A malicious attacker who is able present SM2 content for decryption to an application could cause attacker chosen data to overflow the buffer by up to a maximum of 62 bytes altering the contents of other data held after the buffer, possibly changing application behaviour or causing the application to crash. The location of the buffer is application dependent but is typically heap allocated. Fixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k).

CVE-2021-3711 Affected Openssl src Versions

1 component(s)
Fixed Versions:
111.16.0
Product / Package Ecosystem Affected Versions Fixed Version
openssl-src
 crates.io
< 111.16.0
111.16.0

References

NVD — CVE-2021-3711 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3711
Openssl src Security Information SECURITY
https://www.tenable.com/security/tns-2022-02
Openssl src Security Information SECURITY
https://www.tenable.com/security/tns-2021-16
Openssl src Security Information SECURITY
https://www.oracle.com/security-alerts/cpuoct2021.html
Openssl src Security Information SECURITY
https://www.oracle.com/security-alerts/cpujan2022.html
Openssl src Security Information SECURITY
https://www.oracle.com/security-alerts/cpuapr2022.html
www.openssl.org/news/secadv/2021082... WEB
https://www.openssl.org/news/secadv/20210824.txt
Openssl src Security Information SECURITY
https://www.debian.org/security/2021/dsa-4963
Openssl src Security Information SECURITY
https://security.netapp.com/advisory/ntap-20240621-0006
Openssl src Security Information SECURITY
https://security.netapp.com/advisory/ntap-20211022-0003
Openssl src Security Information SECURITY
https://security.netapp.com/advisory/ntap-20210827-0010
Openssl src Security Information SECURITY
https://security.gentoo.org/glsa/202210-02
Openssl src Security Information SECURITY
https://security.gentoo.org/glsa/202209-02
rustsec.org/advisories/rustsec-... WEB
https://rustsec.org/advisories/RUSTSEC-2021-0097.html
lists.apache.org/thread.html/rad5d9f... WEB
https://lists.apache.org/thread.html/rad5d9f83f0d11fb3f8bb148d179b8a9ad7c6a17f18d70e5805a713d1@%3Cdev.tomcat.apache.org%3E
lists.apache.org/thread.html/rad5d9f... WEB
https://lists.apache.org/thread.html/rad5d9f83f0d11fb3f8bb148d179b8a9ad7c6a17f18d70e5805a713d1%40%3Cdev.tomcat.apache.org%3E
lists.apache.org/thread.html/r18995d... WEB
https://lists.apache.org/thread.html/r18995de860f0e63635f3008fd2a6aca82394249476d21691e7c59c9e@%3Cdev.tomcat.apache.org%3E
lists.apache.org/thread.html/r18995d... WEB
https://lists.apache.org/thread.html/r18995de860f0e63635f3008fd2a6aca82394249476d21691e7c59c9e%40%3Cdev.tomcat.apache.org%3E
git.openssl.org/gitweb/ WEB
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=59f5e75f3bced8fc0e130d72a3f582cf7b480b46
git.openssl.org/gitweb/ WEB
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=59f5e75f3bced8fc0e130d72a3f582cf7b480b46
cert-portal.siemens.com/productcert/pdf/ssa... WEB
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
Openssl src Security Information SECURITY
http://www.openwall.com/lists/oss-security/2021/08/26/2

Frequently Asked Questions

What is CVE-2021-3711?
CVE-2021-3711 is a security vulnerability in Openssl src involving SM2 Decryption Buffer Overflow under CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow').
Which Openssl src versions are affected?
Affected versions include releases prior to 111.16.0 across affected packages: openssl-src.
What version fixes CVE-2021-3711?
Upgrading to 111.16.0 (or the latest patched release for your respective branch) resolves the vulnerability.
Is openssl-src affected?
Yes, openssl-src is affected in releases prior to 111.16.0. Upgrade your dependency to 111.16.0 or later.
What is the CVSS score of CVE-2021-3711?
CVE-2021-3711 has a CVSS v3.1 base score of 9.8 (CRITICAL) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
What CWE is associated with CVE-2021-3711?
CVE-2021-3711 is classified under CWE-120: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') (The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.).
How can I check crates.io dependencies for CVE-2021-3711?
Run the dependency tree command: 'inspect dependencies for openssl-src'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
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  "id" : "GHSA-5ww6-px42-wc85",
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  "published" : "2022-05-24T19:12:03Z",
  "aliases" : [ "CVE-2021-3711" ],
  "summary" : "SM2 Decryption Buffer Overflow",
  "details" : "In order to decrypt SM2 encrypted data an application is expected to call the API function EVP_PKEY_decrypt(). Typically an application will call this function twice. The first time, on entry, the \"out\" parameter can be NULL and, on exit, the \"outlen\" parameter is populated with the buffer size required to hold the decrypted plaintext. The application can then allocate a sufficiently sized buffer and call EVP_PKEY_decrypt() again, but this time passing a non-NULL value for the \"out\" parameter. A bug in the implementation of the SM2 decryption code means that the calculation of the buffer size required to hold the plaintext returned by the first call to EVP_PKEY_decrypt() can be smaller than the actual size required by the second call. This can lead to a buffer overflow when EVP_PKEY_decrypt() is called by the application a second time with a buffer that is too small. A malicious attacker who is able present SM2 content for decryption to an application could cause attacker chosen data to overflow the buffer by up to a maximum of 62 bytes altering the contents of other data held after the buffer, possibly changing application behaviour or causing the application to crash. The location of the buffer is application dependent but is typically heap allocated. Fixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
  } ],
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  "references" : [ {
    "type" : "ADVISORY",
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  }, {
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    "url" : "https://www.tenable.com/security/tns-2021-16"
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    "type" : "WEB",
    "url" : "https://www.oracle.com/security-alerts/cpuoct2021.html"
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  }, {
    "type" : "WEB",
    "url" : "https://www.debian.org/security/2021/dsa-4963"
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    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20240621-0006"
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    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20211022-0003"
  }, {
    "type" : "WEB",
    "url" : "https://security.netapp.com/advisory/ntap-20210827-0010"
  }, {
    "type" : "WEB",
    "url" : "https://security.gentoo.org/glsa/202210-02"
  }, {
    "type" : "WEB",
    "url" : "https://security.gentoo.org/glsa/202209-02"
  }, {
    "type" : "WEB",
    "url" : "https://rustsec.org/advisories/RUSTSEC-2021-0097.html"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/rad5d9f83f0d11fb3f8bb148d179b8a9ad7c6a17f18d70e5805a713d1@%3Cdev.tomcat.apache.org%3E"
  }, {
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    "url" : "https://lists.apache.org/thread.html/rad5d9f83f0d11fb3f8bb148d179b8a9ad7c6a17f18d70e5805a713d1%40%3Cdev.tomcat.apache.org%3E"
  }, {
    "type" : "WEB",
    "url" : "https://lists.apache.org/thread.html/r18995de860f0e63635f3008fd2a6aca82394249476d21691e7c59c9e@%3Cdev.tomcat.apache.org%3E"
  }, {
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  }, {
    "type" : "WEB",
    "url" : "https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=59f5e75f3bced8fc0e130d72a3f582cf7b480b46"
  }, {
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    "url" : "https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=59f5e75f3bced8fc0e130d72a3f582cf7b480b46"
  }, {
    "type" : "WEB",
    "url" : "https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf"
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  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-120" ],
    "severity" : "CRITICAL",
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    "github_reviewed_at" : "2022-06-17T00:06:51Z",
    "nvd_published_at" : "2021-08-24T15:15:00Z"
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}