CVE-2021-3712: Openssl src Read Buffer Overruns Processing ASN.1 Vulnerability

HIGH
Advisory Identifier: GHSA-q9wj-f4qw-6vfj
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CVSS 7.4
CWE-125
Published
Advisory Summary

CVE-2021-3712 is a HIGH (CVSS 7.4) read buffer overruns processing asn.1 vulnerability (CWE-125: Out-of-bounds Read) affecting Openssl src libraries in the crates.io ecosystem. The issue involves read buffer overruns processing asn.1 strings. Remediation is available by upgrading affected packages to version 111.16.0.

CVE-2021-3712 at a Glance

CVE Identifier CVE-2021-3712
GHSA Identifier GHSA-q9wj-f4qw-6vfj
Severity HIGH
CVSS v3.1 Base Score 7.4
CWE Classification CWE-125: Out-of-bounds Read
Affected Product Openssl src
Package Ecosystem crates.io
Published Date
Last Updated

Security Impact

CVSS: 7.4

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

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

How to Fix CVE-2021-3712

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-2021-3712, 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 & RFC 5280 Specification

Under RFC 5280 specifications for X.509 certificates, the Name Constraints extension defines a namespace within which all subsequent subject names in a certification path must be located. Constraints apply to various name forms including directory names, IP addresses, rfc822Name (email addresses), and uniformResourceIdentifier (URI) entries. Specifically, during certificate path validation, affected versions of Openssl src failed to properly normalize or enforce boundary checks when domain names contained trailing dot (.) characters. Because domain names with a trailing dot signify fully qualified domain names (FQDNs), this omission allowed non-conforming certificates to be improperly validated as compliant with the defined name constraints.

Source Advisory Statement

ASN.1 strings are represented internally within OpenSSL as an ASN1_STRING structure which contains a buffer holding the string data and a field holding the buffer length. This contrasts with normal C strings which are repesented as a buffer for the string data which is terminated with a NUL (0) byte. Although not a strict requirement, ASN.1 strings that are parsed using OpenSSL's own "d2i" functions (and other similar parsing functions) as well as any string whose value has been set with the ASN1_STRING_set() function will additionally NUL terminate the byte array in the ASN1_STRING structure. However, it is possible for applications to directly construct valid ASN1_STRING structures which do not NUL terminate the byte array by directly setting the "data" and "length" fields in the ASN1_STRING array. This can also happen by using the ASN1_STRING_set0() function. Numerous OpenSSL functions that print ASN.1 data have been found to assume that the ASN1_STRING byte array will be NUL terminated, even though this is not guaranteed for strings that have been directly constructed. Where an application requests an ASN.1 structure to be printed, and where that ASN.1 structure contains ASN1_STRINGs that have been directly constructed by the application without NUL terminating the "data" field, then a read buffer overrun can occur. The same thing can also occur during name constraints processing of certificates (for example if a certificate has been directly constructed by the application instead of loading it via the OpenSSL parsing functions, and the certificate contains non NUL terminated ASN1_STRING structures). It can also occur in the X509_get1_email(), X509_REQ_get1_email() and X509_get1_ocsp() functions. If a malicious actor can cause an application to directly construct an ASN1_STRING and then process it through one of the affected OpenSSL functions then this issue could be hit. This might result in a crash (causing a Denial of Service attack). It could also result in the disclosure of private memory contents (such as private keys, or sensitive plaintext). Fixed in OpenSSL 1.1.1j (Affected 1.1.1-1.1.1k). Fixed in OpenSSL 1.0.2za (Affected 1.0.2-1.0.2y).

CVE-2021-3712 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-2021-3712 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-3712
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
Openssl src Security Information SECURITY
https://www.openwall.com/lists/oss-security/2021/08/26/2
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-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-2021-0098.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2021/09/msg00021.html
lists.debian.org/debian-lts-announce... WEB
https://lists.debian.org/debian-lts-announce/2021/09/msg00014.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
kc.mcafee.com/corporate/index WEB
https://kc.mcafee.com/corporate/index?page=content&id=SB10366
git.openssl.org/gitweb/ WEB
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=ccb0a11145ee72b042d10593a64eaf9e8a55ec12
git.openssl.org/gitweb/ WEB
https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=94d23fcff9b2a7a8368dfe52214d5c2569882c11
git.openssl.org/gitweb/ WEB
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=ccb0a11145ee72b042d10593a64eaf9e8a55ec12
git.openssl.org/gitweb/ WEB
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=94d23fcff9b2a7a8368dfe52214d5c2569882c11
cert-portal.siemens.com/productcert/pdf/ssa... WEB
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf
cert-portal.siemens.com/productcert/pdf/ssa... WEB
https://cert-portal.siemens.com/productcert/pdf/ssa-244969.pdf
cert-portal.siemens.com/productcert/html/ss... WEB
https://cert-portal.siemens.com/productcert/html/ssa-389290.html
cert-portal.siemens.com/productcert/html/ss... WEB
https://cert-portal.siemens.com/productcert/html/ssa-244969.html
cert-portal.siemens.com/productcert/html/ss... WEB
https://cert-portal.siemens.com/productcert/html/ssa-028723.html
cert-portal.siemens.com/productcert/html/ss... WEB
https://cert-portal.siemens.com/productcert/html/ssa-019200.html

Frequently Asked Questions

What is CVE-2021-3712?
CVE-2021-3712 is a security vulnerability in Openssl src involving Read buffer overruns processing ASN.1 strings under CWE-125: Out-of-bounds Read.
Which Openssl src versions are affected?
Affected versions include releases prior to 111.16.0 across affected packages: openssl-src.
What version fixes CVE-2021-3712?
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-2021-3712?
CVE-2021-3712 has a CVSS v3.1 base score of 7.4 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H.
What CWE is associated with CVE-2021-3712?
CVE-2021-3712 is classified under CWE-125: Out-of-bounds Read (The product reads data past the end, or before the beginning, of the intended buffer.).
How can I check crates.io dependencies for CVE-2021-3712?
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-q9wj-f4qw-6vfj",
  "modified" : "2026-04-27T14:17:36Z",
  "published" : "2022-05-24T19:12:03Z",
  "aliases" : [ "CVE-2021-3712" ],
  "summary" : "Read buffer overruns processing ASN.1 strings",
  "details" : "ASN.1 strings are represented internally within OpenSSL as an ASN1_STRING structure which contains a buffer holding the string data and a field holding the buffer length. This contrasts with normal C strings which are repesented as a buffer for the string data which is terminated with a NUL (0) byte. Although not a strict requirement, ASN.1 strings that are parsed using OpenSSL's own \"d2i\" functions (and other similar parsing functions) as well as any string whose value has been set with the ASN1_STRING_set() function will additionally NUL terminate the byte array in the ASN1_STRING structure. However, it is possible for applications to directly construct valid ASN1_STRING structures which do not NUL terminate the byte array by directly setting the \"data\" and \"length\" fields in the ASN1_STRING array. This can also happen by using the ASN1_STRING_set0() function. Numerous OpenSSL functions that print ASN.1 data have been found to assume that the ASN1_STRING byte array will be NUL terminated, even though this is not guaranteed for strings that have been directly constructed. Where an application requests an ASN.1 structure to be printed, and where that ASN.1 structure contains ASN1_STRINGs that have been directly constructed by the application without NUL terminating the \"data\" field, then a read buffer overrun can occur. The same thing can also occur during name constraints processing of certificates (for example if a certificate has been directly constructed by the application instead of loading it via the OpenSSL parsing functions, and the certificate contains non NUL terminated ASN1_STRING structures). It can also occur in the X509_get1_email(), X509_REQ_get1_email() and X509_get1_ocsp() functions. If a malicious actor can cause an application to directly construct an ASN1_STRING and then process it through one of the affected OpenSSL functions then this issue could be hit. This might result in a crash (causing a Denial of Service attack). It could also result in the disclosure of private memory contents (such as private keys, or sensitive plaintext). Fixed in OpenSSL 1.1.1j (Affected 1.1.1-1.1.1k). Fixed in OpenSSL 1.0.2za (Affected 1.0.2-1.0.2y).",
  "severity" : [ {
    "type" : "CVSS_V3",
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    "url" : "https://rustsec.org/advisories/RUSTSEC-2021-0098.html"
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  }, {
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  }, {
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  }, {
    "type" : "WEB",
    "url" : "https://kc.mcafee.com/corporate/index?page=content&id=SB10366"
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  "database_specific" : {
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    "severity" : "HIGH",
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    "nvd_published_at" : "2021-08-24T15:15:00Z"
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}