CVE-2021-3711 in OpenSSL can allow to change an application’s behavior

The OpenSSL Project patched a high-severity vulnerability, tracked as CVE-2021-3711, that can allow an attacker to change an application’s behavior or cause the app to crash.

The OpenSSL Project released the OpenSSL 1.1.1l version that addresses a high-severity buffer overflow flaw, tracked as CVE-2021-3711, that could allow an attacker to change an application’s behavior or cause the app to crash.

The vulnerability ties the decryption of SM2 encrypted data, the changes depend on the targeted application and data it maintains (i.e. credentials) in the heap while the issue is exploited.

“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).” reads the description for this flaw.

The flaw affects versions prior 1.1.1, it was discovered by John Ouyang.

OpenSSL Project also fixed a medium-severity vulnerability, tracked as CVE-2021-3712, that can be exploited by attackers to trigger a denial-of-service (DoS) condition. The flaw could also result in the disclosure of private memory contents (such as private keys, or sensitive plaintext). The vulnerability affects versions 1.1.1-1.1.1k and was fixed in OpenSSL 1.1.1j and 1.0.2za.

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Pierluigi Paganini

(SecurityAffairs – hacking, CVE-2021-3711)