CVE-2021-3711Not scoredCWE-120

CVE-2021-3711: SM2 Decryption Buffer Overflow

OpenSSL

Vendor fix available · Affected: OpenSSL · Exploitation: likely to be exploited (10% or more)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

87.8%probability of exploitation in the next 30 days

99th percentile

050100

Higher than 99% of scored CVEs

Not scored yet. The CVE record carries no CVSS score.

DescriptionCVE.org

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).

Affected products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

OpenSSL · OpenSSLFixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k)

On the Atlas

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Exploitation: Likely to be exploited (10% or more). EPSS gives it a 10% or higher chance of exploitation in the next 30 days.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Classic Buffer Overflow · Memory Corruption
Vendor: OpenSSL
Published: August 2021
Band: Likely to be exploited (10% or more), August 2021
Bounty reports: 1 disclosed on HackerOne

Disclosed bug bounty reports about CVE-2021-3711

The reports on HackerOne that name this CVE, with HackerOne's own outcome. Titles and metadata only.

CVE-2021-3711: SM2 decrypt buffer overflowInternet Bug Bounty · 2021 · high severityValid

CoverageNo articles yet

No CyberSIXT article names CVE-2021-3711 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.

References

5 more references are in the CVE record.