CVE-2025-7844: wolfTPM library wrapper function `wolfTPM2_RsaKey_TpmToWolf` copies external data to a fixed-size stack buffer without length validation potentially causing stack-based buffer overflow

Vulnerability summary

CVE-2025-7844 is a low (CVSS 1.0) Stack-based Buffer Overflow vulnerability in wolfssl inc. wolftpm. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 4.8% of scored vulnerabilities.

Timeline

1. 04-08-2025
   PublishedVulnerability first disclosed.
2. 05-08-2025
   Last modifiedVulnerability information updated.

Description

Exporting a TPM based RSA key larger than 2048 bits from the TPM could overrun a stack buffer if the default `MAX_RSA_KEY_BITS=2048` is used. If your TPM 2.0 module supports RSA key sizes larger than 2048 bit and your applications supports creating or importing an RSA private or public key larger than 2048 bits and your application calls `wolfTPM2_RsaKey_TpmToWolf` on that key, then a stack buffer could be overrun. If the `MAX_RSA_KEY_BITS` build-time macro is set correctly (RSA bits match what TPM hardware is capable of) for the hardware target, then a stack overrun is not possible.

• CWE-121Stack-based Buffer OverflowThe product writes past the end of a buffer that was allocated on the stack.