Description

This release of Mbed TLS provides new features, bug fixes and minor enhancements. This release includes fixes for security issues.

This release brings in improved multithreaded operations, record-size-limit, and early-data support and other TLS1.3 improvements. TLS1.3 support is now enabled by default.

Long-term support

Mbed TLS 3.6 is a long-term support (LTS) branch. It will be supported with bug-fixes and security fixes until at least March 2027.

Security Advisories

For full details, please see the following link:

• PSA Crypto API with parameters in shared memory

:grey_exclamation: Release notes are trunctuated in GitHub's releases page: Please refer to the 3.6.0 release page.

Release Notes

API changes

• Remove tls13_ in mbedtls_ssl_tls13_conf_early_data() and mbedtls_ssl_tls13_conf_max_early_data_size() API names. Early data feature may not be TLS 1.3 specific in the future. Fixes #6909.

Default behavior changes

• psa_import_key() now only accepts RSA keys in the PSA standard formats. The undocumented ability to import other formats (PKCS#8, SubjectPublicKey, PEM) accepted by the pkparse module has been removed. Applications that need these formats can call mbedtls_pk_parse_{public,}key() followed by mbedtls_pk_import_into_psa().

Requirement changes

• Drop support for Visual Studio 2013 and 2015, and Arm Compiler 5.

New deprecations

• Rename the MBEDTLS_SHA256_USE_A64_CRYPTO_xxx config options to MBEDTLS_SHA256_USE_ARMV8_A_CRYPTO_xxx. The old names may still be used, but are deprecated.
• In the PSA API, domain parameters are no longer used for anything. They are deprecated and will be removed in a future version of the library.
• mbedtls_ecp_write_key() is deprecated in favor of mbedtls_ecp_write_key_ext().

Removals

• In the PSA API, the experimental way to encode the public exponent of an RSA key as a domain parameter is no longer supported. Use psa_generate_key_ext() instead.
• Temporary function mbedtls_pk_wrap_as_opaque() is removed. To mimic the same behavior mbedtls_pk_get_psa_attributes() and mbedtls_pk_import_into_psa() can be used to import a PK key into PSA, while mbedtls_pk_setup_opaque() can be used to wrap a PSA key into a opaque PK context.

Features

• Added an example program showing how to hash with the PSA API.
• Support Armv8-A Crypto Extension acceleration for SHA-256 when compiling for Thumb (T32) or 32-bit Arm (A32).
• AES-NI is now supported in Windows builds with clang and clang-cl. Resolves #8372.
• Add new mbedtls_x509_csr_parse_der_with_ext_cb() routine which allows parsing unsupported certificate extensions via user provided callback.
• Enable the new option MBEDTLS_BLOCK_CIPHER_NO_DECRYPT to omit the decryption direction of block ciphers (AES, ARIA, Camellia). This affects both the low-level modules and the high-level APIs (the cipher and PSA interfaces). This option is incompatible with modes that use the decryption direction (ECB in PSA, CBC, XTS, KW) and with DES.
• Support use of Armv8-A Cryptographic Extensions for hardware acclerated AES when compiling for Thumb (T32) or 32-bit Arm (A32).
• If a cipher or AEAD mechanism has a PSA driver, you can now build the library without the corresponding built-in implementation. Generally speaking that requires both the key type and algorithm to be accelerated or they'll both be built in. However, for CCM and GCM the built-in implementation is able to take advantage of a driver that only accelerates the key type (that is, the block cipher primitive). See docs/driver-only-builds.md for full details and current limitations.
• The CTR_DRBG module will now use AES from a PSA driver if MBEDTLS_AES_C is disabled. This requires PSA_WANT_ALG_ECB_NO_PADDING in addition to MBEDTLS_PSA_CRYPTO_C and PSA_WANT_KEY_TYPE_AES.
• Fewer modules depend on MBEDTLS_CIPHER_C, making it possible to save code size by disabling it in more circumstances. In particular, the CCM and GCM modules no longer depend on MBEDTLS_CIPHER_C. Also, MBEDTLS_PSA_CRYPTO can now be enabled without MBEDTLS_CIPHER_C if all unauthenticated (non-AEAD) ciphers are disabled, or if they're all fully provided by drivers. See docs/driver-only-builds.md for full details and current limitations; in particular, NIST_KW and PKCS5/PKCS12 decryption still unconditionally depend on MBEDTLS_CIPHER_C.
• Add support for record size limit extension as defined by RFC 8449 and configured with MBEDTLS_SSL_RECORD_SIZE_LIMIT. Application data sent and received will be fragmented according to Record size limits negotiated during handshake.
• Improve performance of AES-GCM, AES-CTR and CTR-DRBG when hardware accelerated AES is not present (around 13-23% on 64-bit Arm).
• Add functions mbedtls_ecc_group_to_psa() and mbedtls_ecc_group_from_psa() to convert between Mbed TLS and PSA curve identifiers.
• Add utility functions to manipulate mbedtls_ecp_keypair objects, filling gaps made by making its fields private: mbedtls_ecp_set_public_key(), mbedtls_ecp_write_public_key(), mbedtls_ecp_keypair_calc_public(), mbedtls_ecp_keypair_get_group_id(). Fixes #5017, #5441, #8367, #8652.
• Add functions mbedtls_md_psa_alg_from_type() and mbedtls_md_type_from_psa_alg() to convert between mbedtls_md_type_t and psa_algorithm_t.
• Add partial platform support for z/OS.
• Improve performance for gcc (versions older than 9.3.0) and IAR.
• Add functions mbedtls_ecdsa_raw_to_der() and mbedtls_ecdsa_der_to_raw() to convert ECDSA signatures between raw and DER (ASN.1) formats.
• Add support for using AES-CBC 128, 192, and 256 bit schemes with PKCS#5 PBES2. Keys encrypted this way can now be parsed by PK parse.
• The new function mbedtls_rsa_get_bitlen() returns the length of the modulus in bits, i.e. the key size for an RSA key.
• Add pc files for pkg-config, e.g.: pkg-config --cflags --libs (mbedtls|mbedcrypto|mbedx509)
• Add getter (mbedtls_ssl_session_get_ticket_creation_time()) to access mbedtls_ssl_session.ticket_creation_time.
• The new functions mbedtls_pk_get_psa_attributes() and mbedtls_pk_import_into_psa() provide a uniform way to create a PSA key from a PK key.
• The benchmark program now reports times for both ephemeral and static ECDH in all ECDH configurations.
• Add support for 8-bit GCM tables for Shoup's algorithm to speedup GCM operations when hardware accelerated AES is not present. Improves performance by around 30% on 64-bit Intel; 125% on Armv7-M.
• The new function psa_generate_key_ext() allows generating an RSA key pair with a custom public exponent.
• The new function mbedtls_ecp_write_key_ext() is similar to mbedtls_ecp_write_key(), but can be used without separately calculating the output length.
• Add new accessor to expose the private group id member of mbedtls_ecdh_context structure.
• Add new accessor to expose the MBEDTLS_PRIVATE(ca_istrue) member of mbedtls_x509_crt structure. This requires setting the MBEDTLS_X509_EXT_BASIC_CONSTRAINTS bit in the certificate's ext_types field.
• mbedtls_psa_get_random() is always available as soon as MBEDTLS_PSA_CRYPTO_CLIENT is enabled at build time and psa_crypto_init() is called at runtime. This together with MBEDTLS_PSA_RANDOM_STATE can be used as random number generator function (f_rng) and context (p_rng) in legacy functions.
• The new functions mbedtls_pk_copy_from_psa() and mbedtls_pk_copy_public_from_psa() provide ways to set up a PK context with the same content as a PSA key.
• Add new accessors to expose the private session-id, session-id length, and ciphersuite-id members of mbedtls_ssl_session structure. Add new accessor to expose the ciphersuite-id of mbedtls_ssl_ciphersuite_t structure.Design ref: #8529
• Mbed TLS now supports the writing and reading of TLS 1.3 early data (see docs/tls13-early-data.md). The support enablement is controlled at build time by the MBEDTLS_SSL_EARLY_DATA configuration option and at runtime by the mbedtls_ssl_conf_early_data() API (by default disabled in both cases).
• Add protection for multithreaded access to the PSA keystore and protection for multithreaded access to the the PSA global state, including concurrently calling psa_crypto_init() when MBEDTLS_THREADING_C and MBEDTLS_THREADING_PTHREAD are defined. See docs/architecture/psa-thread-safety/psa-thread-safety.md for more details. Resolves issues #3263 and #7945.

Security

• Fix a stack buffer overread (less than 256 bytes) when parsing a TLS 1.3 ClientHello in a TLS 1.3 server supporting some PSK key exchange mode. A malicious client could cause information disclosure or a denial of service.
• Passing buffers that are stored in untrusted memory as arguments to PSA functions is now secure by default. The PSA core now protects against modification of inputs or exposure of intermediate outputs during operations. This is currently implemented by copying buffers. This feature increases code size and memory usage. If buffers passed to PSA functions are owned exclusively by the PSA core for the duration of the function call (i.e. no buffer parameters are in shared memory), copying may be disabled by setting MBEDTLS_PSA_ASSUME_EXCLUSIVE_BUFFERS. Note that setting this option will cause input-output buffer overlap to be only partially supported (#3266). Fixes CVE-2024-28960.
• Restore the maximum TLS version to be negotiated to the configured one when an SSL context is reset with the mbedtls_ssl_session_reset() API. 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. Fixes #8654 reported by hey3e. Fixes CVE-2024-28755.
• When negotiating TLS version on server side, do not 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 the TLS 1.3-only server in an infinite loop processing a TLS 1.2 ClientHello, resulting in a denial of service. Reported by Matthias Mucha and Thomas Blattmann, SICK AG.
  • If the TLS 1.2 implementation was disabled at runtime, a TLS 1.2 client was able to successfully establish a TLS 1.2 connection with the server. Reported by alluettiv on GitHub. Fixes CVE-2024-28836.

Bugfix

• Fix the build with CMake when Everest or P256-m is enabled through a user configuration file or the compiler command line. Fixes #8165.
• Fix compilation error in C++ programs when MBEDTLS_ASN1_PARSE_C is disabled.
• Fix possible NULL dereference issue in X509 cert_req program if an entry in the san parameter is not separated by a colon.
• Fix possible NULL dereference issue in X509 cert_write program if an entry in the san parameter is not separated by a colon.
• Fix an inconsistency between implementations and usages of __cpuid, which mainly causes failures when building Windows target using mingw or clang. Fixes #8334 & #8332.
• Fix build failure in conda-forge. Fixes #8422.
• Fix parsing of CSRs with critical extensions.
• Switch to milliseconds as the unit for ticket creation and reception time instead of seconds. That avoids rounding errors when computing the age of tickets compared to peer using a millisecond clock (observed with GnuTLS). Fixes #6623.
• Fix TLS server accepting TLS 1.2 handshake while TLS 1.2 is disabled at runtime. Fixes #8593.
• Remove accidental introduction of RSA signature algorithms in TLS Suite B Profile. Fixes #8221.
• Fix unsupported PSA asymmetric encryption and decryption (psa_asymmetric_[en|de]crypt) with opaque keys. Resolves #8461.
• On Linux on ARMv8, fix a build error with SHA-256 and SHA-512 acceleration detection when the libc headers do not define the corresponding constant. Reported by valord577.
• Correct initial capacities for key derivation algorithms:TLS12_PRF, TLS12_PSK_TO_MS, PBKDF2-HMAC, PBKDF2-CMAC
• Fix mbedtls_pk_get_bitlen() for RSA keys whose size is not a multiple of 8. Fixes #868.
• Avoid segmentation fault caused by releasing not initialized entropy resource in gen_key example. Fixes #8809.
• mbedtls_pem_read_buffer() now performs a check on the padding data of decrypted keys and it rejects invalid ones.
• Fix mbedtls_pk_sign(), mbedtls_pk_verify(), mbedtls_pk_decrypt() and mbedtls_pk_encrypt() on non-opaque RSA keys to honor the padding mode in the RSA context. Before, if MBEDTLS_USE_PSA_CRYPTO was enabled and the RSA context was configured for PKCS#1 v2.1 (PSS/OAEP), the sign/verify functions performed a PKCS#1 v1.5 signature instead and the encrypt/decrypt functions returned an error. Fixes #8824.
• Fix missing bitflags in SSL session serialization headers. Their absence allowed SSL sessions saved in one configuration to be loaded in a different, incompatible configuration.
• In TLS 1.3 clients, fix an interoperability problem due to the client generating a new random after a HelloRetryRequest. Fixes #8669.
• Fix the restoration of the ALPN when loading serialized connection with the mbedtls_ssl_context_load() API.
• Fix NULL pointer dereference in mbedtls_pk_verify_ext() when called using an opaque RSA context and specifying MBEDTLS_PK_RSASSA_PSS as key type.
• Fix RSA opaque keys always using PKCS1 v1.5 algorithms instead of the primary algorithm of the wrapped PSA key.
• Fully support arbitrary overlap between inputs and outputs of PSA functions. Note that overlap is still only partially supported when MBEDTLS_PSA_ASSUME_EXCLUSIVE_BUFFERS is set (#3266).

Changes

• Use heap memory to allocate DER encoded public/private key. This reduces stack usage significantly for writing a public/private key to a PEM string.
• PSA_WANT_ALG_CCM and PSA_WANT_ALG_CCM_STAR_NO_TAG are no more synonyms and they are now treated separately. This means that they should be individually enabled in order to enable respective support; also the corresponding MBEDTLS_PSA_ACCEL symbol should be defined in case acceleration is required.
• Moved declaration of functions mbedtls_ecc_group_to_psa and mbedtls_ecc_group_of_psa from psa/crypto_extra.h to mbedtls/psa_util.h
• mbedtls_pk_sign_ext() is now always available, not just when PSA (MBEDTLS_PSA_CRYPTO_C) is enabled.
• Extended PSA Crypto configurations options for FFDH by making it possible to select only some of the parameters / groups, with the macros PSA_WANT_DH_RFC7919_XXXX. You now need to defined the corresponding macro for each size you want to support. Also, if you have an FFDH accelerator, you'll need to define the appropriate MBEDTLS_PSA_ACCEL macros to signal support for these domain parameters.
• RSA support in PSA no longer auto-enables the pkparse and pkwrite modules, saving code size when those are not otherwise enabled.
• mbedtls_mpi_exp_mod and code that uses it, notably RSA and DHM operations, have changed their speed/memory compromise as part of a proactive security improvement. The new default value of MBEDTLS_MPI_WINDOW_SIZE roughly preserves the current speed, at the expense of increasing memory consumption.
• Rename directory containing Visual Studio files from visualc/VS2013 to visualc/VS2017.
• The TLS 1.3 protocol is now enabled in the default configuration.

Who should update

We recommend all users should update to take advantage of the bug fixes contained in this release at an appropriate point in their development lifecycle.

Note

:grey_exclamation: mbedtls-3.6.0.tar.bz2 are our official release files. source.tar.gz and source.zip are automatically generated snapshot's that github is generating. They do not include external depedencies, and can't be configured

Checksum

The SHA256 hashes for the archives are:

3ecf94fcfdaacafb757786a01b7538a61750ebd85c4b024f56ff8ba1490fcd38 mbedtls-3.6.0.tar.bz2