CVE-2021-3712: Debian Linux

High severity, CVSS 7.4. EPSS: 50.4% chance of exploitation in the next 30 days.

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).

Affected products

Debian Debian Linux: version 9.0 only; version 10.0 only; version 11.0 only
McAfee Epolicy Orchestrator: before 5.10.0 (fixed in 5.10.0); version 5.10.0 only
Netapp Clustered Data Ontap: affected versions not specified
Netapp Clustered Data Ontap Antivirus Connector: affected versions not specified
Netapp E-Series Santricity OS Controller: from 11.0, up to and including 11.50.2
Netapp Hci Management Node: affected versions not specified
Netapp Manageability Software Development Kit: affected versions not specified
Netapp Santricity Smi-S Provider: affected versions not specified
Netapp Solidfire: affected versions not specified
Netapp Storage Encryption: affected versions not specified
OpenSSL OpenSSL: from 1.0.2, before 1.0.2za (fixed in 1.0.2za); from 1.1.1, before 1.1.1l (fixed in 1.1.1l)
Oracle Communications Cloud Native Core Console: version 1.9.0 only
Oracle Communications Cloud Native Core Security Edge Protection Proxy: version 1.7.0 only
Oracle Communications Cloud Native Core Unified Data Repository: version 1.15.0 only
Oracle Communications Session Border Controller: version 8.4 only; version 9.0 only
Oracle Communications Unified Session Manager: version 8.2.5 only; version 8.4.5 only
Oracle Enterprise Communications Broker: version 3.2.0 only; version 3.3.0 only
Oracle Enterprise Session Border Controller: version 8.4 only; version 9.0 only
Oracle Essbase: before 11.1.2.4.047 (fixed in 11.1.2.4.047); from 21.0, before 21.3 (fixed in 21.3); version 21.3 only
Oracle Health Sciences Inform Publisher: version 6.2.1.0 only; version 6.3.1.1 only
Oracle Jd Edwards Enterpriseone Tools: before 9.2.6.3 (fixed in 9.2.6.3)
Oracle Jd Edwards World Security: version a9.4 only
Oracle MySQL Connectors: up to and including 8.0.27
Oracle MySQL Enterprise Monitor: up to and including 8.0.25
Oracle MySQL Server: from 5.7.0, up to and including 5.7.35; from 8.0.0, up to and including 8.0.26
and 7 more

Published 2021-08-24. Last modified 2026-06-17.