Mbed TLS up to 2.16.10/2.26.x lignum.c mbedtls_mpi_exp_mod risky encryption

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Mbed TLS up to 2.16.10/2.26.x. The impacted element is the function mbedtls_mpi_exp_mod of the file lignum.c. This manipulation causes risky encryption. This vulnerability appears as CVE-2021-36647. The attack requires local access. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Mbed TLS up to 2.16.10/2.26.x. Affected by this vulnerability is the function mbedtls_mpi_exp_mod of the file lignum.c. The manipulation with an unknown input leads to a risky encryption vulnerability. The CWE definition for the vulnerability is CWE-327. The product uses a broken or risky cryptographic algorithm or protocol. As an impact it is known to affect confidentiality. The summary by CVE is:

Use of a Broken or Risky Cryptographic Algorithm in the function mbedtls_mpi_exp_mod() in lignum.c in Mbed TLS Mbed TLS all versions before 3.0.0, 2.27.0 or 2.16.11 allows attackers with access to precise enough timing and memory access information (typically an untrusted operating system attacking a secure enclave such as SGX or the TrustZone secure world) to recover the private keys used in RSA.

The weakness was presented 01/18/2023. It is possible to read the advisory at tls.mbed.org. This vulnerability is known as CVE-2021-36647 since 07/12/2021. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1600 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 240979 (Debian dla-4236 : libmbedcrypto3 - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 2.16.11, 2.27.0 or 3.0.0 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (240979). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

• Mbed

Name

• TLS

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6
• 2.7
• 2.8
• 2.9
• 2.10
• 2.11
• 2.12
• 2.13
• 2.14
• 2.15
• 2.16
• 2.16.0
• 2.16.1
• 2.16.2
• 2.16.3
• 2.16.4
• 2.16.5
• 2.16.6
• 2.16.7
• 2.16.8
• 2.16.9
• 2.16.10
• 2.17
• 2.18
• 2.19
• 2.20
• 2.21
• 2.22
• 2.23
• 2.24
• 2.25
• 2.26

CPE 2.3info

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CPE 2.2info

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Entryinfo

Be aware that VulDB is the high quality source for vulnerability data.

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