9.8

CVSS Score

3.1

-

CVSS Score

Basic Information

CVE ID

CVE-2021-3711

GHSA ID

GHSA-5ww6-px42-wc85

EPSS Score

0.85711%

CWE

CWE-120

Published

5/24/2022

Updated

6/24/2024

KEV Status

Technology

Rust

Basic Information

CVE ID

GHSA ID

EPSS Score

CWE

Published

Updated

KEV Status

Technology

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CVE-2021-3711

CVE-2021-3711: SM2 Decryption Buffer Overflow

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).

(GitHub Advisory)

Miggo Vulnerability Database

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CVE-2021-3711

CVE-2021-3711:

9.8

CVSS Score

3.1

-

CVSS Score

Basic Information

CVE ID

CVE-2021-3711

GHSA ID

GHSA-5ww6-px42-wc85

EPSS Score

0.85711%

CWE

CWE-120

Published

5/24/2022

Updated

6/24/2024

KEV Status

Technology

Rust

Basic Information

CVE ID

GHSA ID

EPSS Score

CWE

Published

Updated

KEV Status

Technology

Technical Details

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
openssl-src	rust	< 111.16.0	111.16.0

Technical Details

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability stemmed from incorrect buffer size calculation in sm2_plaintext_size, which was called during the first EVP_PKEY_decrypt invocation. The function used cryptographic parameters rather than parsing actual ciphertext, leading to undersized allocations. pkey_sm2_decrypt facilitated this incorrect calculation by passing the wrong parameters. The patch fundamentally changes both the function signature and implementation to properly parse ciphertext structure.

Vulnerable functions

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WAF Protection Rules

WAF Rule

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Reasoning

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9.8

-

Basic Information

Basic Information

Concerned about an active attack path?

CVE-2021-3711: SM2 Decryption Buffer Overflow

CVE-2021-3711:

9.8

-

Basic Information

Basic Information

Technical Details

Technical Details

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

WAF Protection Rules

WAF Rule

Reasoning

Vulnerability IntelligenceMiggo AI

Basic Information

Basic Information

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

WAF Protection Rules

WAF Rule

Reasoning

CVE-2021-3711: SM2 Decryption Buffer Overflow

Technical Details

9.8

9.8

Vulnerability Intelligence
Miggo AI

Vulnerability Intelligence
Miggo AI

Vulnerability Intelligence
Miggo AI