Two potential heap out-of-bounds write locations existed in DecodeObjectId() in wolfcrypt/src/asn.c. First, a bounds check only validates one available slot before writing two OID arc values (out[0] and out[1]), enabling a 2-byte out-of-bounds write when outSz equals 1. Second, multiple callers pass sizeof(decOid) (64 bytes on 64-bit platforms) instead of the element count MAX_OID_SZ (32), causing the function to accept crafted OIDs with 33 or more arcs that write past the end of the allocated buffer.
Bug 1 (off-by-one) affects any code calling DecodeObjectId() with an output buffer of size 1. Bug 2 (sizeof mismatch) is reachable via network when wolfSSL is compiled with HAVE_OID_DECODING or WOLFSSL_ASN_PRINT, and WC_ASN_UNKNOWN_EXT_CB is enabled with a registered unknown extension callback.
Do not enable WC_ASN_UNKNOWN_EXT_CB or do not register an unknown extension callback if not required. This mitigates the network-reachable variant (Bug 2) but does not address Bug 1.
Fix Bug 1: Add a bounds check requiring at least 2 output slots before writing the first OID arc split (y == 0 case). Fix Bug 2: Change callers to pass the element count (MAX_OID_SZ) instead of sizeof(decOid) as the output buffer size parameter.