CVE-2021-3712

Read buffer overruns processing ASN.1 strings

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Published Aug 24, 2021 CVSS 3.1 · 7.4 High EPSS 48.1% KEV · Not listed
Description
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 1.1.1l (Affected 1.1.1-1.1.1k). Fixed in OpenSSL 1.0.2za (Affected 1.0.2-1.0.2y).

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-2766-1 openssl security update
Debian DLA Debian DLA DLA-2774-1 openssl1.0 security update
Debian DSA Debian DSA DSA-4963-1 openssl security update
EUVD EUVD EUVD-2022-4935 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 1.1.1l (Affected 1.1.1-1.1.1k). Fixed in OpenSSL 1.0.2za (Affected 1.0.2-1.0.2y).
Github GHSA Github GHSA GHSA-q9wj-f4qw-6vfj Read buffer overruns processing ASN.1 strings
Ubuntu USN Ubuntu USN USN-5051-1 OpenSSL vulnerabilities
Ubuntu USN Ubuntu USN USN-5051-2 OpenSSL vulnerability
Ubuntu USN Ubuntu USN USN-5051-3 OpenSSL vulnerability
Ubuntu USN Ubuntu USN USN-5088-1 EDK II vulnerabilities
Ubuntu USN Ubuntu USN USN-7894-1 EDK II vulnerabilities
References
Link Providers
http://www.openwall.com/lists/oss-security/2021/08/26/2 cve-icon cve-icon
https://cert-portal.siemens.com/productcert/html/ssa-019200.html cve-icon
https://cert-portal.siemens.com/productcert/html/ssa-028723.html cve-icon
https://cert-portal.siemens.com/productcert/html/ssa-244969.html cve-icon
https://cert-portal.siemens.com/productcert/html/ssa-389290.html cve-icon
https://cert-portal.siemens.com/productcert/pdf/ssa-244969.pdf cve-icon cve-icon
https://cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf cve-icon cve-icon
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=94d23fcff9b2a7a8368dfe52214d5c2569882c11 cve-icon cve-icon
https://git.openssl.org/gitweb/?p=openssl.git%3Ba=commitdiff%3Bh=ccb0a11145ee72b042d10593a64eaf9e8a55ec12 cve-icon cve-icon
https://kc.mcafee.com/corporate/index?page=content&id=SB10366 cve-icon cve-icon
https://lists.apache.org/thread.html/r18995de860f0e63635f3008fd2a6aca82394249476d21691e7c59c9e%40%3Cdev.tomcat.apache.org%3E cve-icon cve-icon
https://lists.apache.org/thread.html/rad5d9f83f0d11fb3f8bb148d179b8a9ad7c6a17f18d70e5805a713d1%40%3Cdev.tomcat.apache.org%3E cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2021/09/msg00014.html cve-icon cve-icon
https://lists.debian.org/debian-lts-announce/2021/09/msg00021.html cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2021-3712 cve-icon
https://security.gentoo.org/glsa/202209-02 cve-icon cve-icon
https://security.gentoo.org/glsa/202210-02 cve-icon cve-icon
https://security.netapp.com/advisory/ntap-20210827-0010/ cve-icon cve-icon
https://security.netapp.com/advisory/ntap-20240621-0006/ cve-icon cve-icon
https://www.cve.org/CVERecord?id=CVE-2021-3712 cve-icon
https://www.debian.org/security/2021/dsa-4963 cve-icon cve-icon
https://www.openssl.org/news/secadv/20210824.txt cve-icon cve-icon cve-icon
https://www.oracle.com/security-alerts/cpuapr2022.html cve-icon cve-icon
https://www.oracle.com/security-alerts/cpujan2022.html cve-icon cve-icon
https://www.oracle.com/security-alerts/cpuoct2021.html cve-icon cve-icon
https://www.tenable.com/security/tns-2021-16 cve-icon cve-icon
https://www.tenable.com/security/tns-2022-02 cve-icon cve-icon
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
Metrics epss

{'score': 0.00722}

 epss

{'score': 0.00814}
Type Values Removed Values Added
First Time appeared Redhat acm
CPEs cpe:/a:redhat:acm:2.4::el8
Vendors & Products Redhat acm
Type Values Removed Values Added
CPEs cpe:/a:redhat:acm:2.4::el8
Vendors & Products Redhat acm
Weaknesses

Sources

Status
PUBLISHED
Assigner
openssl
Published
Updated
Apr 16, 2026, 2:11 PM
Reserved
Aug 16, 2021, 12:00 AM

View source JSON

Updated
Aug 3, 2024, 5:01 PM

JSON

Status
Modified
Published
Aug 24, 2021, 3:15 PM
Modified
Jun 17, 2026, 4:05 AM

View source JSON

Severity
Moderate
Public date
Aug 24, 2021, 12:00 AM

View source Bugzilla JSON

No data.