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Out-of-bounds Read


Severity High
Score 9.1/10


An issue was discovered in Mbed TLS before 2.28.2 and 3.x before 3.2.0. In some configurations, an unauthenticated attacker can send an invalid ClientHello message to a DTLS server that causes a HEAP-BASED BUFFER OVER-READ of up to 255 bytes. This can cause a server crash or possibly information disclosure based on error responses. Affected configurations have "MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE" enabled and "MBEDTLS_SSL_IN_CONTENT_LEN" less than a threshold that depends on the configuration: 258 bytes if using "mbedtls_ssl_cookie_check", and possibly up to 571 bytes with a custom cookie check function.

  • LOW
  • NONE
  • NONE
  • NONE
  • HIGH
  • HIGH

CWE-125 - Out-of-Bounds Read

Out-of-bounds read is a vulnerability that allows access to memory beyond the authorized accessible location. Such a vulnerability compromises the confidentiality of the trusted environment in the application and enables an attacker to launch further attacks by leveraging the exposed information.

Advisory Timeline

  • Published