Mbed TLS before 3.6.4 has a PEM parsing one-byte heap-based buffer underflow, in mbedtls_pem_read_buffer and two mbedtls_pk_parse functions, via untrusted PEM input.

In MbedTLS 3.3.0 before 3.6.4, mbedtls_lms_import_public_key does not check that the input buffer is at least 4 bytes before reading a 32-bit field, allowing a possible out-of-bounds read on truncated input. Specifically, an out-of-bounds read in mbedtls_lms_import_public_key allows context-dependent attackers to trigger a crash or limited adjacent-memory disclosure by supplying a truncated LMS (Leighton-Micali Signature) public-key buffer under four bytes. An LMS public key starts with a 4-byte type indicator. The function mbedtls_lms_import_public_key reads this type indicator before validating the size of its input.

In MbedTLS 3.3.0 before 3.6.4, mbedtls_lms_verify may accept invalid signatures if hash computation fails and internal errors go unchecked, enabling LMS (Leighton-Micali Signature) forgery in a fault scenario. Specifically, unchecked return values in mbedtls_lms_verify allow an attacker (who can induce a hardware hash accelerator fault) to bypass LMS signature verification by reusing stale stack data, resulting in acceptance of an invalid signature. In mbedtls_lms_verify, the return values of the internal Merkle tree functions create_merkle_leaf_value and create_merkle_internal_value are not checked. These functions return an integer that indicates whether the call succeeded or not. If a failure occurs, the output buffer (Tc_candidate_root_node) may remain uninitialized, and the result of the signature verification is unpredictable. When the software implementation of SHA-256 is used, these functions will not fail. However, with hardware-accelerated hashing, an attacker could use fault injection against the accelerator to bypass verification.

Mbed TLS before 2.28.10 and 3.x before 3.6.3, on the client side, accepts servers that have trusted certificates for arbitrary hostnames unless the TLS client application calls mbedtls_ssl_set_hostname.

Mbed TLS 3.5.x through 3.6.x before 3.6.2 has a buffer underrun in pkwrite when writing an opaque key pair

An issue was discovered in Mbed TLS 3.x before 3.6.1. With TLS 1.3, when a server enables optional authentication of the client, if the client-provided certificate does not have appropriate values in if keyUsage or extKeyUsage extensions, then the return value of mbedtls_ssl_get_verify_result() would incorrectly have the MBEDTLS_X509_BADCERT_KEY_USAGE and MBEDTLS_X509_BADCERT_KEY_USAGE bits clear. As a result, an attacker that had a certificate valid for uses other than TLS client authentication would nonetheless be able to use it for TLS client authentication. Only TLS 1.3 servers were affected, and only with optional authentication (with required authentication, the handshake would be aborted with a fatal alert).

An issue was discovered in Mbed TLS before 2.28.9 and 3.x before 3.6.1, in which the user-selected algorithm is not used. Unlike previously documented, enabling MBEDTLS_PSA_HMAC_DRBG_MD_TYPE does not cause the PSA subsystem to use HMAC_DRBG: it uses HMAC_DRBG only when MBEDTLS_PSA_CRYPTO_EXTERNAL_RNG and MBEDTLS_CTR_DRBG_C are disabled.

In Mbed TLS 3.3.0 through 3.5.2 before 3.6.0, a malicious client can cause information disclosure or a denial of service because of a stack buffer over-read (of less than 256 bytes) in a TLS 1.3 server via a TLS 3.1 ClientHello.

An issue was discovered in Mbed TLS 3.5.x before 3.6.0. When negotiating the TLS version on the server side, it can fall back to the TLS 1.2 implementation of the protocol if it is disabled. If the TLS 1.2 implementation was disabled at build time, a TLS 1.2 client could put a TLS 1.3-only server into an infinite loop processing a TLS 1.2 ClientHello, resulting in a denial of service. If the TLS 1.2 implementation was disabled at runtime, a TLS 1.2 client can successfully establish a TLS 1.2 connection with the server.

An issue was discovered in Mbed TLS 3.5.x before 3.6.0. When an SSL context was reset with the mbedtls_ssl_session_reset() API, the maximum TLS version to be negotiated was not restored to the configured one. An attacker was able to prevent an Mbed TLS server from establishing any TLS 1.3 connection, potentially resulting in a Denial of Service or forced version downgrade from TLS 1.3 to TLS 1.2.

An issue was discovered in Mbed TLS 2.18.0 through 2.28.x before 2.28.8 and 3.x before 3.6.0, and Mbed Crypto. The PSA Crypto API mishandles shared memory.

Integer Overflow vulnerability in Mbed TLS 2.x before 2.28.7 and 3.x before 3.5.2, allows attackers to cause a denial of service (DoS) via mbedtls_x509_set_extension().

An issue was discovered in Mbed TLS 2.x before 2.28.7 and 3.x before 3.5.2. There was a timing side channel in RSA private operations. This side channel could be sufficient for a local attacker to recover the plaintext. It requires the attacker to send a large number of messages for decryption, as described in "Everlasting ROBOT: the Marvin Attack" by Hubert Kario.

An issue was discovered in Mbed TLS 3.5.1. There is persistent handshake denial if a client sends a TLS 1.3 ClientHello without extensions.

An issue was discovered in Mbed TLS through 3.5.1. In mbedtls_ssl_session_reset, the maximum negotiable TLS version is mishandled. For example, if the last connection negotiated TLS 1.2, then 1.2 becomes the new maximum.

Mbed TLS 3.2.x through 3.4.x before 3.5 has a Buffer Overflow that can lead to remote Code execution.

Mbed TLS 2.x before 2.28.5 and 3.x before 3.5.0 has a Buffer Overflow.

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.

An issue was discovered in Mbed TLS before 2.28.2 and 3.x before 3.3.0. There is a potential heap-based buffer overflow and heap-based buffer over-read in DTLS if MBEDTLS_SSL_DTLS_CONNECTION_ID is enabled and MBEDTLS_SSL_CID_IN_LEN_MAX > 2 * MBEDTLS_SSL_CID_OUT_LEN_MAX.

An issue was discovered in Mbed TLS before 2.28.2 and 3.x before 3.3.0. An adversary with access to precise enough information about memory accesses (typically, an untrusted operating system attacking a secure enclave) can recover an RSA private key after observing the victim performing a single private-key operation, if the window size (MBEDTLS_MPI_WINDOW_SIZE) used for the exponentiation is 3 or smaller.