CVE-2026-87044 Fuga de memoria en el shim criptográfico de Mbed TLS ante operaciones de cifrado/AEAD fallidas provoca…
El driver shim criptográfico de Mbed TLS en drivers/crypto/crypto_mbedtls_shim.c maneja operaciones multiparte de cifrado y AEAD de PSA. En mbedtls_cbc() y mbedtls_aead(), toda ruta de error posterior a un psa_cipher_encrypt_setup() / psa_aead_decrypt_setup() exitoso retornaba directamente sin llamar a psa_cipher_abort() / psa_aead_abort(). Como el abort es lo único que llega a mbedtls_cipher_free(), cada operación fallida fugaba permanentemente el mbedtls_aes_context asignado en el heap (unos 288 bytes) desde el…
CVSS 3.1
- Probabilidad de explotación · EPSS del 09/110,2 % · percentil 11
- Explotada activamenteNo confirmada
- Exploit públicoNo conocido
Afectados
zephyrproject zephyr
desde 4.4.0 hasta antes de 4.5.0
Qué hacer
- Verificá si usás zephyr y en qué versión.
- Actualizá a la versión corregida que indique el fabricante en su aviso o aplicá su mitigación.
- Revisá registros y accesos de los sistemas expuestos para descartar un uso previo.
Calculadora CVSS
CVSS 3.1 · 6.5 MEDIA
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Vector de ataqueRed adyacente
- Complejidad del ataqueBaja
- Privilegios requeridosNinguno
- Interacción del usuarioNinguna
- AlcanceSin cambio
- ConfidencialidadNinguna
- IntegridadNinguna
- DisponibilidadAlta
Descripción original
The Mbed TLS crypto shim driver in drivers/crypto/crypto_mbedtls_shim.c drives PSA multipart cipher and AEAD operations. In mbedtls_cbc() and mbedtls_aead(), every error path after a successful psa_cipher_encrypt_setup() / psa_aead_decrypt_setup() returned directly without calling psa_cipher_abort() / psa_aead_abort(). Because the abort is the only thing that reaches mbedtls_cipher_free(), each failed operation permanently leaked the heap-allocated mbedtls_aes_context (roughly 288 bytes) that setup had allocated from Mbed TLS's fixed static heap (_mbedtls_heap[CONFIG_MBEDTLS_HEAP_SIZE], default 512 bytes). With CONFIG_PSA_CRYPTO_PROVIDER_TFM the leaked object is instead a finite secure-partition multipart-operation slot.
The failure is chosen by an unauthenticated attacker. With CONFIG_NET_L2_IEEE802154_SECURITY backed by this driver, ieee802154_decrypt_auth() in subsys/net/l2/ieee802154/ieee802154_security.c invokes cipher_ccm_op() on every received secured frame, with no authentication ahead of the MIC check. A device in radio range can transmit a stream of syntactically valid 802.15.4 frames carrying a bogus MIC; each one makes psa_aead_verify() fail and leaks a block. The CBC path is reachable the same way through the OSDP secure channel, where CONFIG_OSDP_SC_ENABLED selects this shim and osdp_encrypt() / osdp_decrypt() leave out_buf_max unset, so every operation fails inside psa_cipher_update().
Exhausting the Mbed TLS heap — which the default configuration reaches after a couple of failed operations, and any realistic configuration reaches in well under a second of frames — makes all subsequent mbedtls_calloc() calls fail. Every later cryptographic operation in the image then fails permanently, including link-layer security and any TLS/DTLS sharing the same heap, until the device is rebooted. There is no memory corruption or information disclosure: frames with an invalid MIC are still rejected, so the impact is limited to availability.
The fix routes all post-setup failures in mbedtls_cbc() and mbedtls_aead() through a common error: label that calls the matching PSA abort before returning. Setup failures need no change, since the PSA core aborts the operation itself when setup fails.
Referencias (2)
Resumen traducido automáticamente de la descripción original. Fuente: Nureq Monitor. Cómo funciona.