renesas on SecMate Bloghttps://blog.secmate.dev/tags/renesas/What we find. What we share.Hugoen-usnoreply@blog.secmate.dev//blog.secmate.dev/ (SecMate Team)Sat, 25 Jul 2026 09:06:45 +0000Memory Safety Vulnerabilities in Renesas FSP Cryptographic and Networking Codehttps://blog.secmate.dev/posts/renesas-fsp-vulnerabilities/Thu, 23 Apr 2026 04:00:00 +0000Maxime Rossi BellomRamtine Tofighi ShiraziSecurityVulnerability ResearchEmbeddedhttps://blog.secmate.dev/posts/renesas-fsp-vulnerabilities/SecMate found seven vulnerabilities in Renesas FSP, including flaws in RSA verification, AES-XTS finalization, GCM decrypt handling, and the RMAC receive path.Memory Safety Vulnerabilities in Renesas FSP Cryptographic and Networking Code

SecMate found seven vulnerabilities in Renesas FSP [1] , the Flexible Software Package for Renesas RA microcontrollers [2] . FSP is the vendor software stack for RA devices and bundles BSP code, HAL drivers, middleware, and security integrations, including hardware-backed cryptography and Mbed TLS support.

FSP layered architecture: BSP, HAL drivers, middleware, security modules, and RTOS support

In the v6.1.0 FSP codebase we analyzed at commit ed247f90fb9bc390ebd36f1a0b7847b0ff44f322 [3] , we found issues in RSA verification, the hardware-accelerated AES-XTS path, GCM decrypt handling, and the RMAC receive path. These are implementation flaws in FSP integration code around hardware-backed cryptography and networking. They are not flaws in AES, GCM, CCM, XTS, or RSA as algorithms.

Advisory Map

Area Vulnerability SecMate Advisory Renesas Advisory
RMAC Read buffer overflow in r_rmac.c SECMATE-2025-0021 renesas/fsp#431
RSA Signature verification pointer underflow in r_sce_rsa.c SECMATE-2025-0019 renesas/fsp#423
AES-XTS Encrypt and decrypt finalization overflows in aes_alt_process.c SECMATE-2025-0020 renesas/fsp#427
GCM Tag length buffer overflow in gcm_alt_process.c SECMATE-2025-0022 renesas/fsp#428
CCM Tag length buffer overflow in ccm_alt_process.c SECMATE-2025-0023 renesas/fsp#430
CCM adaptor MAC length buffer overflow in r_sce_AES_adapt.c SECMATE-2025-0024 renesas/fsp#429

The AES-XTS advisory covers two findings, one in the encrypt finalization path and one in the decrypt finalization path.

Affected Builds and Use Cases

SecMate’s published disclosure advisories are available on the SecMate disclosures page [4] . The table above links both the SecMate advisory and the corresponding Renesas public advisory for each vulnerability group.

These cryptography-related findings do not apply to every RA build. In FSP, the accelerated AES and AEAD paths are compiled for devices with SCE5, SCE5B, SCE7, SCE9, or RSIP support, and the XTS path is excluded on RA2 parts.

In downstream products, these APIs may be used for signature verification, authenticated decryption, encrypted storage, firmware update, or other security-sensitive processing. Exposure therefore depends on whether untrusted inputs can reach those wrappers.

The RMAC finding is separate from the cryptographic code paths. It affects products using the Ethernet receive API if application code provides a buffer smaller than the received frame.

Renesas PSIRT acknowledged the reports and published public advisories on GitHub.

Recommendations

  • If you use affected RA builds, review the Renesas advisories and update to FSP v6.3.0 or later.
  • In downstream products, check whether untrusted inputs can reach FSP wrappers used for signature verification, authenticated decryption, encrypted storage, or firmware update handling.
  • Add negative tests for malformed signatures, AEAD metadata, XTS lengths, and oversized Ethernet frames.
  • If you use r_rmac, verify that receive buffers are sized for the largest frame your product accepts.

Timeline

October 20, 2025
SecMate reports the seven FSP vulnerabilities against commit ed247f90fb9bc390ebd36f1a0b7847b0ff44f322 (v6.1.0).
December 18, 2025
Renesas releases FSP v6.3.0, which contains the public fixes [5].
February 4, 2026
Renesas confirms that the FSP disclosure track covered all seven reported FSP vulnerabilities and that each would receive its own advisory.
February 10, 2026
Renesas tells SecMate the public FSP advisories were published on GitHub.

Takeaway

The common thread is not broken cryptography. It is memory safety in the FSP code that exposes cryptographic and Ethernet functionality to RA applications. Hardware-backed cryptography still depends on the surrounding integration code.

For the full list of our disclosures, see our disclosure page [4] . If you are building embedded systems and want to find vulnerabilities before attackers do, reach out .

References

  • [1] Renesas. “Renesas Flexible Software Package.” GitHub. Repository

  • [2] Renesas. “Renesas Flexible Software Package Documentation.” Documentation

  • [3] Renesas. “FSP v6.1.0 analyzed commit” (ed247f90fb9bc390ebd36f1a0b7847b0ff44f322). Commit

  • [4] SecMate. “Disclosures.” Disclosure page

  • [5] Renesas. “FSP v6.3.0.” GitHub Releases. Release

The SecMate Team

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