Executive brief
Mbed TLS is a widely used security library that provides encryption and SSL/TLS capabilities for embedded devices and applications. A vulnerability in how the library processes digital certificate names could allow an attacker to crash the system or, in some specialized environments like microcontrollers, potentially take control of the device. This could lead to service outages or unauthorized access to sensitive equipment.
Technical details
A NULL pointer dereference exists in the mbedtls_x509_string_to_names() function, which is also reachable via CSR and CRT subject/issuer name setting functions. The vulnerability is triggered when a memory allocation failure occurs during parsing, leading to a memcpy() call with a NULL destination address (address 0). On systems with memory protection, this results in a segmentation fault (DoS); however, on microcontrollers without such protections, writing to address 0 may overwrite interrupt vectors, potentially allowing arbitrary code execution. The issue is fixed in Mbed TLS versions 3.6.6 and 4.1.0.
Affected products
- TrustedFirmware Mbed TLS 3.5.0 to 3.6.5, 4.0.0
Timeline
- 2026-03-31: advisory: Vendor security advisory published
- 2026-04-01: disclosed: CVE published to NVD